Arguably 1handers can feint faster without a shield though, if someone is using one of the slower shields, right? If true, this would lend to their "speediness without a shield" imo.
As for the OP's suggestion, I for one think adding the unbalanced tag to 1handers is something that is long overdue. It is a pretty fun mechanic for adding diversity to the weapon selection. However I wouldn't necessarily agree with buffing their speed insanely and lowering their cut damage... then they go from "slow/strong shield breakers" to "unbalanced 3-directional swords that are good against shields." Instead I would just buff their damage and maybe tweak the speed a little bit accordingly. Maybe make some unbalanced/faster and make some unbalanced/stronger so that there is some variety among them instead of them all being slow or all being fast. The low-tier axes could be the faster shield breakers while the expensive ones with huge heads could be the slower ones that pack a punch. The same could be done to some maces, imo. Make some like the outclassed iberian unbalanced but stronger compared to the balanced spathovaklion (and please ffs remove that thing's stab).