Though Trey did manage to become Nerevarine, he did it mostly through superior sneakiness and managing to create a really nasty sword. I'm not sure his borderline psychosis would allow him to prevail in a stand-up fight. Then, too, there is the fact that he is a walking potion factory....
Even if a mechanism was developed to put all the characters into an arena-situation (I rather like the Hircine idea), he is such a stubborn [deleted] that he would probably refuse to participate- he may not FIGHT as well as some, but he can POUT better than any other character out there

Might be fun, though.