Would Kass be broken if his Q gave a general shield?

Not until his Q become a skillshot or smtg.

Yes he would be broken. He already deals absurd damage once he starts scaling. If he could be picked into any match-up to just safely farm early, he'd quickly become pick or ban.

probably not. since he will mostly be picked against ap mages. anyway the duration of the shield is too low. even viktor shield. is unreliable. since you have to land an ability. and the scaling on both of them is not that great at all. might as well just get a rod of ages instead. anyway i built kassadin tank. iceborn and frozen heart. and hes pretty good against ad champs. anyway kassadin needs buffs right now. am not saying he can't be good. but it takes too much work and hes not intuitive nor safe to play. hes an assassin that can all in a lot of squishies but hes too vulnerable after he ults. with league of too much damage alot of other assassins can burst him even faster while being way tankier. they just need to remove his Q completely and give him something else. its currently useless in every way. t

No i think it would make him much more viable. More in line with how strong every other mid laner is. It would, in essence, bring him up to being level with everyone else imo