Umm....if you have trouble with his physical attacks I suppose you could use Auto-Protect or Sentinel. Also Luck can really help in this battle.

And the spoiler I said, it doesn't have anything to do with the ending or the storyline. It's just something that people who haven't beaten Trema might not know.

EDIT: Sorry, it's been a long time and I can't remember exactly what happens after Trema is beaten.