"You can't take it from me!" The mirror can't help the incredulous statement, betraying his panic at the idea in this few words. What would happen if something went wrong and Gabriel wasn't around to help him? He'd be dead, that's what.

As for making his case, William briefly has to think about it, watching as the dagger vanishes into Gabriel's vest. At least he least he'd been honest about the stabbing part.

"It was given to me. By Gabriel, just in case. Give it back. "