Quote Originally Posted by Rad Bromance View Post
mainly because the game won't allow you to get so powered up that you kill him in three turns.
Well, I killed (SPOILER)Orphan's final form in 1,5 minutes during the first stagger and got the 5-star rating on the first attempt, so it is possible (with tier2 weapons, of course, but you can get them after chapter 12, cause at that time you should have enough gil from the drops).