When I ask a teacher about that, I learn that when it comes to divine-attack and barrier magic, that the Milis Religious Order seems to be the only ones who have the rights to be teaching higher level magic in those fields.
The academy is limited to only an elementary level class on the subject.
I was told I couldn't learn how to use a physical barrier here, since physical barriers were considered an intermediate level technique.
While the teacher can use it, it would be a violation if they were to teach it to others.
If it comes out that there was a violation committed, it's possible that they will be excommunicated from the Milis religion, and may face a heresy inquisition.
It seems that originally even a beginner level class on these two subjects were not allowed before, however about two years ago, provided certain conditions were followed, limited teaching was authorized.
Because of such limiting circumstances, it seems the focus of the class shifts more to the methods of how magical barriers can be broken instead.
Barrier properties are anti-physical and anti-magical, it's said that if a person is a Saint-class and above, they can combine the properties of both barriers and create one with a special trait.
Also, barriers have various purposes, such as for the sake of defending oneself and for the sake of imprisoning other things.
Roxy had spoken to me a little about barriers, back then, I didn't really understand what she meant about barriers, and I guess I more or less ended up ignoring that part.
With that being the case, I end up studying from the beginning, and it also serves as a review.