Well, I am about a quarter through the game (or so I think), and am now facing Seymore. I just can't seem to beat him, he's quite difficult. When he brings out his aeon, the Pain attack kills me every time, and I can't, generally cope with him.

He just confuses my players, and I can't attack him without (fifty percent of the time) hitting my own characters.

Any ideas how I can defeat him?