I would say that is a bit...They should just make it so if u hit a person with a bone you get a 2 sec stun but there were to be a cooldown
random, but in other ways
Anyways:
I understand that skills like blackjack may be unbalanced when you are unlucky..
It would probably make more sense to balance the class in other ways, so that blackjack is either something really unimportant that happens once in a while, or something really important which happens all the time..
It would make sense to not base a class's balance on chance based skills, but that don't mean they need to be removed