Well, the thing is it's not so simple, like it's weak so after a buff it isn't OP.
What are you going to buff. Speed, they are fast enough (giving the sidesword or steel pick +5 speed might be broken), reach - no ghost reach, stun you could maybe change and damage. But it would be kind of silly to do more damage with 1h than with 2h.
Only thing that makes sense is make them a better (or at least equal) choice as sidearm. Make shields, bows, crossbows more expensive and 1h weapons cheaper. Start every char with 40 1h wpf (but make shield decrease 1h wpf, maybe that could be used to diversify shields too).
Urlukurs suggestion is nice too.