@Glomoro
I originally assumed it would be a part of the curriculum, which doesn't seem to be the case, but they might add it later, as you said. I had a look at the chapter again, rather than that she's fighting dirty, they're more surprised at her using her whole body and whether they taught unarmed combat at their school. I'm not aware of the setting in regards to how they treat different sexes, but it could be related to it being an all-girl's school. Anyways, the confusion from the other characters doesn't seem to be based off people being able to fight unarmed, but rather the female MC being able to fight unarmed - for whatever cultural reason.
I haven't read any martial arts mangas, so it's interesting that swordsmen aren't considered masters until they can treat their body as a weapon - though I can see where it comes from (e.g. to be a master of the sword, you have to master your body first since the sword is treated as an extension of the body).