High HP build Plus rage with this move = big time abuse it is extremely OP.
Every class has a list of must haves, and a stun move in the tree is one of them. By adding this OP move you would also be removing TLM and bounty hunters stun move.
Not supported. It would be OP and every class has a stun skill. Removing it from BH and TLM wouldn't be fair. 1 Turn cool down wouldn't be enough unless it had a two or three turn warm up and a two to three turn cool down since it does 50% extra damage as you said it would. Making it OP and abused on 1st turn. Same reason as Mother1 said. A OP move players will abuse with a Health abuse build.