Fantasy novel that I once found at a library but for the life of me can't remember the name of the book or the author. It centers around a boy named Cain or CAne or KAin I believe and his two friends. It starts off with them being trained in some weird place by monks(?) and with a weird regime. He's a master martial artist. His two friends are a deformed archer kid and trained spy kid with a crossbow.
Does this ring any bells?