Crossbowman is what he says he is I guess, he literally shoots his crossbow and that’s about it. He even has a sword and shield hanging from him because he doesn’t trust himself with his crossbow. If the character can’t trust himself then you shouldn’t use him.
He has a low chance to stun a single target but it’s just pointless don’t waste resources on this champion you’ll regret it like many have done so in the past. Do not waste books or masteries on this champion only use him for food!