A man can waste much time with an apparatus criticus and alternate readings. From Hamlet (1.1.39-43).

I could continue expanding references and commentary (and I wish I had the Andrews edition to add) but the short is that no one has any clear answer and everyone is willing to entertain a Shakespearean coinage – either by novel transference of meaning (using ‘harrow’ from the agricultural implement) or outright new verb formation. Accordingly, I make less an ass of myself in adding my own conjecture and connecting Q2’s ‘horrowes’ with Latin ‘horrere.’ Lewis and Short define here but I’ll cite the similar and possibly more relevant Dictionary of Medieval Latin from British Sources definition (with full usage illustrations in the link):

1 to bristle; b (fig.). c to stand up like spikes.
2 to shudder, shiver.
3 to be or become horrible, shocking, disgusting. 
4 to be or become horrified.

With that in mind, advance to Hamlet’s first encounter with the Ghost (1.4.55ish):

What may this mean,
That thou, dead corse, again in complete steel
Revisit’st thus the glimpses of the moon,
Making night hideous; and we fools of nature
So horridly to shake our disposition
With thoughts beyond the reaches of our souls?

The Arden editors gloss horridly thus:

horrendously (a stronger meaning than modern ‘horrid’, possibly with a glance at the literal meaning of Latin horridus, bristing or with hair standing on end: see 1.5.19-20).

Here I would add that the DMLBS entry for horridus includes the additional sense ‘causing horror, dreadful.’ And that, bearing in mind the etymological connection with horrere and the above ‘shudder, shiver’ sense of the word, one can posit a clear play in line 55’s ‘so horridly to shake.’

Now to the second half of Hamlet’s encounter with the Ghost:

But that I am forbid
To tell the secrets of my prison-house,
I could a tale unfold whose lightest word
Would harrow up thy soul, freeze thy young blood,
Make thy two eyes, like stars, start from their spheres,
Thy knotted and combined locks to part
And each particular hair to stand on end,
Like quills upon the fretful porpentine:

Here there is no issue with the textual history – harrow is the universal reading – so I would instead draw attention to the hair imagery, which we’ve seen above is latent in the first two appearances of the ghost and directly connects to the imagery of horrere.

My vanity’s proposal is twofold. First, the less defensible element, that the harrow of 1.5 contaminated the reading of horrowes in 1.1. The only reason for preferring harrow is deference to the OED – that it feels less bold to add a new sense to an existing word than create a new one altogether. Second, that the root senses of horrere at least lurk as background associations in all three appearances of the Ghost – most expressly in the first (by my reading ‘horrowes’), more subtly in the second (submerged in ‘horridly’ but activated by ‘shake’), and as a verbal echo harrow/horrow/horrere triggered by hair-standing imagery in the third. All accomplished by a man with little Latin.

And this is why I stick to extracts. Playful and pointless argumentation takes too long.

From Julius Caesar (3.1).

CASSIUS
Where is Antony?
TREBONIUS
Fled to his house amazed:
Men, wives and children stare, cry out and run
As it were doomsday.
BRUTUS
Fates, we will know your pleasures:
That we shall die, we know; ’tis but the time
And drawing days out, that men stand upon.
CASSIUS
Why, he that cuts off twenty years of life
Cuts off so many years of fearing death.
BRUTUS
Grant that, and then is death a benefit:
So are we Caesar’s friends, that have abridged
His time of fearing death. Stoop, Romans, stoop,
And let us bathe our hands in Caesar’s blood
Up to the elbows, and besmear our swords:
Then walk we forth, even to the market-place,
And, waving our red weapons o’er our heads,
Let’s all cry ‘Peace, freedom and liberty!’
CASSIUS
Stoop, then, and wash. How many ages hence
Shall this our lofty scene be acted over
In states unborn and accents yet unknown!
BRUTUS
How many times shall Caesar bleed in sport,
That now on Pompey’s basis lies along
No worthier than the dust!

I find this scene one of the most terrifying miniatures in all Shakespeare’s psychological portraiture. A single line pushes Brutus from a predictable – from the classical rhetoric perspective – over-reasoned justification (‘So are we Caesar’s friends, that have abridged / His time of fearing death’) to a surreal dissociative break (Stoop, Romans, stoop, / And let us bathe our hands in Caesar’s blood … waving our red weapons o’er our heads, / Let’s all cry ‘Peace, freedom and liberty!’). Cassius’ attempted realigning of the ‘lofty scene’ as future exemplar flops out as Brutus picks up the performative-iterative element only to ritualise the slaughter over the exemplar – “How many times shall Caesar bleed in sport.” Any possible value of the action is here submerged in the character’s inability to focus on anything but the blood. The bathing in blood is not in Plutarch or any other source.

From As You Like It (2.7), a possible epitaph.

….and in his brain,
Which is as dry as the remainder biscuit
After a voyage, he hath strange places cramm’d
With observation, the which he vents
In mangled forms.

I swore there was a pun on ‘biscuit’ and ‘cramm’d’ until I remembered that cram was a Tolkien creation.

From Henry V (4.4)

SCENE IV. The field of battle.
Alarum. Excursions. Enter PISTOL, French Soldier, and Boy

PISTOL
Yield, cur!

French Soldier
Je pense que vous etes gentilhomme de bonne qualite.

PISTOL
Qualtitie calmie custure me! Art thou a gentleman?
what is thy name? discuss.

French Soldier
O Seigneur Dieu!

PISTOL
O, Signieur Dew should be a gentleman:
Perpend my words, O Signieur Dew, and mark;
O Signieur Dew, thou diest on point of fox,
Except, O signieur, thou do give to me
Egregious ransom.

French Soldier
O, prenez misericorde! ayez pitie de moi!

PISTOL
Moy shall not serve; I will have forty moys;
Or I will fetch thy rim out at thy throat
In drops of crimson blood.

French Soldier
Est-il impossible d’echapper la force de ton bras?

PISTOL
Brass, cur!
Thou damned and luxurious mountain goat,
Offer’st me brass?
French Soldier

O pardonnez moi!

PISTOL
Say’st thou me so? is that a tun of moys?
Come hither, boy: ask me this slave in French
What is his name.

Boy
Ecoutez: comment etes-vous appele?

French Soldier
Monsieur le Fer.

Boy
He says his name is Master Fer.

PISTOL
Master Fer! I’ll fer him, and firk him, and ferret
him: discuss the same in French unto him.

Boy
I do not know the French for fer, and ferret, and firk.

PISTOL
Bid him prepare; for I will cut his throat.

French Soldier
Que dit-il, monsieur?

Boy
Il me commande de vous dire que vous faites vous
pret; car ce soldat ici est dispose tout a cette
heure de couper votre gorge.

PISTOL
Owy, cuppele gorge, permafoy,
Peasant, unless thou give me crowns, brave crowns;
Or mangled shalt thou be by this my sword.

French Soldier
O, je vous supplie, pour l’amour de Dieu, me
pardonner! Je suis gentilhomme de bonne maison:
gardez ma vie, et je vous donnerai deux cents ecus.

PISTOL
What are his words?

Boy
He prays you to save his life: he is a gentleman of
a good house; and for his ransom he will give you
two hundred crowns.

PISTOL
Tell him my fury shall abate, and I the crowns will take.

French Soldier
Petit monsieur, que dit-il?

Boy
Encore qu’il est contre son jurement de pardonner
aucun prisonnier, neanmoins, pour les ecus que vous
l’avez promis, il est content de vous donner la
liberte, le franchisement.

French Soldier
Sur mes genoux je vous donne mille remercimens; et
je m’estime heureux que je suis tombe entre les
mains d’un chevalier, je pense, le plus brave,
vaillant, et tres distingue seigneur d’Angleterre.

PISTOL
Expound unto me, boy.

Boy
He gives you, upon his knees, a thousand thanks; and
he esteems himself happy that he hath fallen into
the hands of one, as he thinks, the most brave,
valorous, and thrice-worthy signieur of England.

PISTOL
As I suck blood, I will some mercy show.
Follow me!

Boy
Suivez-vous le grand capitaine.

From Much Ado About Nothing (2.1) – far my favorite of the comedies for the dynamic between Benedick and Beatrice (the latter described by Leonato below)

There’s little of the melancholy element in her, my
lord: she is never sad but when she sleeps, and
not ever sad then; for I have heard my daughter say,
she hath often dreamed of unhappiness and waked
herself with laughing.

For the scene (4.1) where they admit their feelings for one another my Arden edition quotes this perfect analysis – “They manage by a deft indirectness to put nothing into a syntax where the other person can choose either its negative or its positive meaning” (Jorgensen in Redeeming Shakespeare’s Words) – that is also the tactical summation of the merry war that is my marriage.

The 2011 David Tennant/Catherine Tate production is well worth a view but – because I’m a purist and the 80s Gibraltar resettling rubs me wrong – even better is the David Tennant/Samantha Spiro 2005 BBC Radio production. Honorable mention goes to Michael Keaton as Dogberry in the 90s Branagh film.

From Henry IV pt. 2 (4.4):

LANCASTER
Fare you well, Falstaff: I, in my condition,
Shall better speak of you than you deserve.

Exeunt all but Falstaff

FALSTAFF
I would you had but the wit: ’twere better than
your dukedom. Good faith, this same young sober-
blooded boy doth not love me; nor a man cannot make
him laugh; but that’s no marvel, he drinks no wine.
There’s never none of these demure boys come to any
proof; for thin drink doth so over-cool their blood,
and making many fish-meals, that they fall into a
kind of male green-sickness; and then when they
marry, they get wenches: they are generally fools
and cowards; which some of us should be too, but for
inflammation. A good sherris sack hath a two-fold
operation in it. It ascends me into the brain;
dries me there all the foolish and dull and curdy
vapours which environ it; makes it apprehensive,
quick, forgetive, full of nimble fiery and
delectable shapes, which, delivered o’er to the
voice, the tongue, which is the birth, becomes
excellent wit. The second property of your
excellent sherris is, the warming of the blood;
which, before cold and settled, left the liver
white and pale, which is the badge of pusillanimity
and cowardice; but the sherris warms it and makes
it course from the inwards to the parts extreme:
it illumineth the face, which as a beacon gives
warning to all the rest of this little kingdom,
man, to arm; and then the vital commoners and
inland petty spirits muster me all to their captain,
the heart, who, great and puffed up with this
retinue, doth any deed of courage; and this valour
comes of sherris. So that skill in the weapon is
nothing without sack, for that sets it a-work; and
learning a mere hoard of gold kept by a devil, till
sack commences it and sets it in act and use.
Hereof comes it that Prince Harry is valiant; for
the cold blood he did naturally inherit of his
father, he hath, like lean, sterile and bare land,
manured, husbanded and tilled with excellent
endeavour of drinking good and good store of fertile
sherris, that he is become very hot and valiant. If
I had a thousand sons, the first humane principle I
would teach them should be, to forswear thin
potations and to addict themselves to sack.

I’d like to know whether any specific reference – folklore or literary – is behind the line ‘a mere hoard of gold kept by a devil.’ Both my Arden and my Oxford texts go no further than ‘alludes to the superstition that buried treasure was guarded by evil spirits’ but that somehow isn’t satisfying. There seems to me an alchemical reference of sorts where knowledge (as gold) is imprisoned (hoarded by a devil) until the right chemical agent (sack – below praised for its ‘warming’ virtues) induces the reaction that first stirs (commences) then sets it moving (in act and use).

From Henry IV pt.2 (3.1):

O God! that one might read the book of fate,
And see the revolution of the times
Make mountains level, and the continent,
Weary of solid firmness, melt itself
Into the sea! and, other times, to see
The beachy girdle of the ocean
Too wide for Neptune’s hips; how chances mock,
And changes fill the cup of alteration
With divers liquors! O, if this were seen,
The happiest youth, viewing his progress through,
What perils past, what crosses to ensue,
Would shut the book, and sit him down and die.

From The Merchant of Venice, Bassanio’s reasoning as he puzzles through the test for Portia’s hand:

So may the outward shows be least themselves:
The world is still deceived with ornament.
In law, what plea so tainted and corrupt,
But, being seasoned with a gracious voice,
Obscures the show of evil? In religion,
What damned error, but some sober brow
Will bless it and approve it with a text,
Hiding the grossness with fair ornament?
There is no vice so simple but assumes
Some mark of virtue on his outward parts:
How many cowards, whose hearts are all as false
As stairs of sand, wear yet upon their chins
The beards of Hercules and frowning Mars;
Who, inward search’d, have livers white as milk;
And these assume but valour’s excrement
To render them redoubted! Look on beauty,
And you shall see ’tis purchased by the weight;
Which therein works a miracle in nature,
Making them lightest that wear most of it:
So are those crisped snaky golden locks
Which make such wanton gambols with the wind,
Upon supposed fairness, often known
To be the dowry of a second head,
The skull that bred them in the sepulchre.
Thus ornament is but the guiled shore
To a most dangerous sea; the beauteous scarf
Veiling an Indian beauty; in a word,
The seeming truth which cunning times put on
To entrap the wisest.