It became obvious that he was incorrect about something. She wasn't just handling it too calmly. Not only did she chuckle lightly, she was upping her week count. Did she want to die? While she had seemed entertained when at the guillotine, he didn't really think anyone could enjoy their own pain.
He released her hand, moving to cover her mouth and hold the knife to her neck instead. "This knife came with a letter from my uncle, telling me to deal with you myself. I don't think he's expecting you to return." He imagined, at least, that Mobius wouldn't be expecting him to chicken out. And he wasn't chickening out so much as he didn't want to needlessly dirty his room any further. A body wouldn't be too hard to dispose of in their era, but he didn't really want to have to at that moment. By any luck her injuries would get so infected that she'd die of something on her own anyway. Certainly she wouldn't go back to his uncle's home now. Right?
Though part of the reason he stopped there, he figured, was that she was enjoying the moment a bit too much. The situation was in his control and he wasn't going to allow her to take that from him by getting any amusement out of it. Michel took a step away from her, but he still held the knife to her chin as he looked down at her. "Get out."