A few things, though they would probably drastically change how the classes play.

Warrior:

Remove stance requirements on all the V stack moves.

Dark Knight:

Lower the MP consumption of Darkside.
Lower the MP costs of all the MP consuming moves by about 50% to give Drk more MP to play with and placing less emphasis on the MP game.

Paladin:

Give them another attack that requires MP to use on single target. On the average boss with no adds, Pld has no reason to use any of their MP at all. I'd like to give pld some sort of damage dealing move that requires them to use some MP. I don't want pld to have to play the MP game like drk does, but I'd like to give pld some other reason to use their MP.