Sinful realized his blunder. He was indeed already aware of Jack's dual-class from World Maker's data. The fight with Luther had been abrupt. He had heard the commotion and immediately lent a hand because he didn't want Jack to be killed. The order was to capture Jack alive. Jack might not die for real but that was also an opportunity to further gain Jack's trust. He didn't realize that one misstep had blown his cover.
"Hm, you are not wearing Amulet of Rebirth?" Jack said. "Good! Save me the time from hunting you down. This should teach you, disgusting psycho, from threatening my friend."
Jack swung his sword down. A puff of smoke burst out when Jack's sword hit Sinful's body. No, not a body. It was a piece of wood!
"What the…"