"It shall not be long but I'll be here again."
"Thou liest thou shag-ear'd villain."
Both Singer and Dyce read hair'd, and I think rightly. Hair was originally pronounced hear, under which form it occurs in two of Shakespeare's older plays; so shag-heared and 'shag-eared' would sound exactly alike.
Sc. 3.
"You may deserve of him, and wisdom 'twere."
A syllable has plainly been lost. For 'deserve,' the correction of Theobald, the folio has discern.