Setsuna's brother is forgetting something really important. Martial Arts is merely a tool to achieve violence. Setsuna isn't teaching Akita Martial Arts, she's teaching him violence at it's most purest state
I know the head slam was to show Amane's growth but it could have been done in different way honestly, it just made Suzuki look incompetent. A much better way to to have done it is if Suzuki wasn't around and happened to see it after the fact or maybe far enough to not be able to do something
At this point, if Liz and Miyabi don't end up together, I'm gonna be so pissed. Get yourself a man that will literally ignite the flames of industrial revolution for you