Brutal Blackjack

I know that the other edges that enhances choke (warrior) and strange (assassin) significantly increases the damage to MANGLE or beyond. In contrast, the brutal blackjack edge doesn't do much and it's significantly expensive. Before I lodge a suggestion/complaint about brutal blackjack, was wondering if this may be a bug. I'm weapon blackjacking with a weight 29 weapon. You hit a citizen of Udgaard in the back of the head with the hilt of the claw of the Dracolich. You step out of the shadows. You stop walking gently. You trample around loudly again. Your blackjack DISMEMBERS a citizen of Udgaard! A citizen of Udgaard is covered with bleeding wounds.