My party was

Vaan lvl 45 Sword/shield - heavy armor
Fran lvl 44 Bow - cloth
Balthier lvl 44 - Gun - lightarmor and cloth hat

I went for his devices right away and manage to kill them pretty quick with regular attacks. I then just started pounding on him with his health dropping rappidly. And before I knew it was over, no quickenings and summons needed at all. He didn't went "beserk" either.

I hope this helps.