We have with a leaven'd and prepared choice.

"Leaven'd" has no sense in this place: we should read "Level'd
choice". The allusion is to archery, when a man has fixed upon his
object, after taking good aim.--Warburton.

No emendation is necessary. "leaven'd choice" is one of Shakespeare's
harsh metaphors. His train of ideas seems to be this. "I have proceeded
to you with choice mature, concocted, fermented, leaven'd." When
Bread is "leaven'd", it is left to ferment: a "leavn'd" choice is
therefore a choice not hasty, but considerate, not declared as soon
as it fell into the imagination, but suffered to work long in the
mind. Thus explained, it suits better with "prepared" than "levelled".

ACT II. SCENE ix. (II. iii. 11-12.)

Who falling in the flaws of her own youth,
Hath blister'd her report.

Who doth not see that the integrity of the metaphor requires we
should read "flames of her own youth."--Warburton.

Who does not see that upon such principles there is no end of
correction.

ACT III. SCENE i. (III. i. 13-15.)

Thou art not noble:
For all th' accommodations, that thou bear'st