I think it would be interesting to incorporate the BLM playstyle into a melee class. instead of def/perry stance I think it would be better to have raw damage stance and tp regen/self buff stance. I also think it would be fun to tie those into combos as well. You build up a buff that will last through the raw damage stance increasing your damage out put. Each time you do the combo for the buff while your TP is recovering it increases the duration. When it comes to cast times it might become hard to use right but that could go into risk = reward. Maybe have certain really strong skills can have cast times like you said, similar to an iaido sword style.