She has been banned from any armor or clothing whatsoever until she passes

"You see, usually the exams at Garreg Mach are to tell whether or not you're able to effectively utilize the weapons, armor and training that we give you. Since you've failed, you've unfortunately proven yourself unable to handle it..."

Bernadetta's eyes seemed to light up, clearly assuming that this meant she could sit out battles and spars due to being unable to use her usual light armor. Unfortunately for her, that was not the only thing she'd be missing.

"... And the armor exam handles all types of attire, from armor, casual attire and even smallclothes. You do, after all, have to understand the protectiveness of even casual clothing in case you get ambushed."

Bernadetta's panic returned, even stronger than before. "W-wait... nonononono, y-you don't mean what I think you mean, do you?", the rapidly paling girl managed to blurt out. Unfortunately for her, all she got was a nod from her unfazed teacher.

"Yes, I believe you know exactly what I mean. For the next week, you have been banned from wearing any clothing whatsoever. Shirts, shoes, underwear, even covering yourself with a towel or sheet; if you are seen attempting to use anything along those lines, you WILL be expelled without any second chances. In addition, any truancy from your classes will also result in expulsion."

This was too much for her. This had to be a joke, right? Some sort of trick?

"P-professor, I- I can't-"

"I know this isn't what you want, Bernadetta. It's going to be a frightening experience. But this is the only way I managed to convince Rhea to allow you to remain. I know you can do this, you just need to be strong."

Unfortunately, Byleth's words rang on deaf ears. Bernadetta's wide open mouth and rolled back eyes indicated that she had passed out at some point while she was speaking.

"Well then... at least that makes starting this reasonably easy..." she pondered, gazing at her student's form. Her entire conversation was, of course, a lie. There was no such thing as an "Armor exam", and Rhea most certainly hadn't been planning on expelling the poor young thing, although she DID enjoy Byleth's little plan for the recluse when she came to her with it. It was actually at the behest of Sothis, the bored, green-haired Goddess within Byleth's mind, that she do this, purely for entertainment. After all, if things went too badly she could simply rewind time to before this conversation had occured.

Pulling out a small dagger, the cruel professor quickly got to work, slicing the **** girls shirt in two, leaving her small, pale breasts fully exposed to the open air. Dropping to her knees, Byleth got to removing her students skirt, before slowly peeling of the extremely form-fitting spats underneath them, revealing her untouched hairless pussy to the world. Finally, the professor got a chair from Bernadetta's desk, placing it outside her room and propping the young girl up on it. Thankfully, there was nobody around at the moment, most students currently in the cafeteria for breakfast.

After removing the comatose girls boots and making sure to keep her legs spread wide, as a nice surprise for any passing by the dorms, Byleth shut the doors on her room, locking it with the master key she had been provided when she had joined the teaching staff. It would be impossible for her to simply re-enter and hide herself away anymore.

Finally sure that the job had been complete, Byleth simply wandered off, content that Bernadetta would have an interesting awakening when she roused. Already, she could hear the sounds of passing students murmuring at the sight, apparently believing the young archer had done this herself.

"I wonder what she'll do when she wakes up?"