The art ruins this entire situation. Toramaru is fully within reach of the knife in those scenes, especially the moment that the knife is pointed right at her. She could have just flung at their hand; dropping stuff on their head is not safer than securing the knife.
I can understand that Toramaru may want to drop the title anyway, but do so after securing your boyfriend first instead of relying on chance and happenstance.
This series is weird. The beginning was strong but at some point it seemed like the author unlearned how to set up and resolve almost all situations the characters are bend into.