Dueryn's definately in the range (due to details of his past that are intended to be revealed later), but he hasn't won a fight yet, so...
The guy I'm unveiling tomorrow has few abilities of his own and relies of bodies he's possessing for those, so I'm not sure how to count him.
Utval is a ten, possibly eleven. He's too innocent and erm... sensitive... to be a major player. He's just the tool.
Garhn is dead anyway.
Zag Tar Gok is assuredly not a Mary Sue. He has about a nine, due to having few powers and being an imbecile.