I finaly manage to beat him (donīt ask me how i did it...but I think one of my other characters was standing in a wrong place somehow ). Thanks for the replies.
About the game itself: Itīs average. Mostly because of the battle system and the linear missions. The story is definitely a lot better than many other J-RPGīs, and thats why I went all the way. I used about 65-70 hours to get through it, and that was more than enough for me.