I dunno, I didn't have any trouble. Try spending more time in duel casting; I started out in relentless attack to slow down the stagger droppage but then pommeling a boss with two Ravegers does some crazy damage. Don't forget to use Libra so your people automatically use the most effective attacks.
I didn't even use Odin. I had used him earlier for fun and hadn't built enough TP back up. xP