Bai Wu's punch indeed went awry because he never had confidence in smashing the crystal in one blow.
Even before the battle began, he had calculated that the finishing blow had to be delivered by the captain.
He used his Evil Fallen transformed body to perfectly block the mummy's line of sight.
At the same time, his shoulder was positioned right at the mummy's weak spot!
Wu Jiu couldn't see where the weak point was, but he understood Bai Wu's intention and struck with his strongest cutting force, aiming right for Bai Wu's shoulder!
The long-accumulated strike thundered down! At the instant Bai Wu's punch missed, a tyrannical blade force sliced right through Bai Wu's entire right arm.
A level seven mutated Evil Fallen body was naturally tough but couldn't withstand Wu Jiu's blade at all.
So much so that after cutting off Bai Wu's right arm, the momentum of the blade still rapidly passed through the left side of the mummy's waist.