does shady spectacles make a unit mighty if it was attached to a non mighty unit copying a mighty unit?

Yes — the equipped unit becomes Mighty, as long as the copied unit's Might is 5 or greater from its copyable traits.

Shady Spectacles' copy effect replaces the equipped unit's copyable traits — including Might (Rule 477.1.b.1.a). "Mighty" just means current Might 5+, so a 1-Might unit copying a 5-Might Baron is now a 5-Might unit and is Mighty (Rules 706–710). Any gear Might bonuses already attached to the equipped unit (other than Spectacles itself) add on top.

One caveat: Might from the target's gear is not copied. If the chosen unit is only "Mighty" because of gear or buffs on it (e.g., a printed 3-Might unit with +3 from equipment), your copy comes in at 3 Might and is not Mighty — copy effects see printed/copied traits only, and Mighty is evaluated from current Might.