Alzano's female uniform is so incomprehensibly Stripperiffic because it was originally designed for Sex MagicIn the setting, much of the knowledge of magic has been lost to time and mages' formal education is very traditional and tends to focus a lot on learning spells by rote without really questioning the underlying mechanics. Add a layer or five of snobbish elitism on top of it, and it becomes entirely too plausible that mages would follow tradition to the letter even for something as obviously ridiculous as the uniforms' design just because admitting otherwise would get others to look at you funny, The Emperor's New Clothes style. With enough time and generations of students graduating from the academy, the oddness becomes the norm and everybody will hardly question it anymore.
Now, why does the girls' uniform look like something a porn actress would wear when parodying mage apprentice to begin with? Probably because that was the whole point at first. Usually Sex Magic involves either invoking The Laws of Association and Contagion or using the emotions generated during the act for magical purposes. Of course, in practice that means getting the participants in the mood in the first place and the combination of mini-skirt, thighhigh socks, garter belts and a Bare Your Midriff blouse not only does the trick but also allows the girl to easily have sex with almost no need to disrobe at all. Pervy and practical.
Sarah is actually the mother of Sisti or be her older sister.Although their surnames are different and we never get any hints of this, Glenn's former lover looks so much like Sisti that out of context one would believe that it's the same person at different ages. Moreover, we were hinted that Sisti's father was a widower, and in-universe author has already used such a strong similarity between mother and daughter in the example of Rumia.
- This is disproven by a light novel side story (and its manga adaptation), which show Sisti's mother. There is no indication that she isn't her biological mother. Moreover, Sara comes from a now-destroyed tribe from a different country, making it unlikely for her to be related to Sisti.