I like that this series just every now and then reminds us that the faculty are accomplished demons in their own right and are likely not people to be trifled with despite most of them being depicted as otherwise mild tempered and goofy. Just a chapter or two ago we saw Robin, the wide-eyed newbie, blast a hole through Ocho, who thinks he was entirely concealed from detection, from the other end of the forest with a smile on his face. And now we have this old teachers' oath and has a tone from a much more chaotic time than what we see. And we also had the terrorists' supposed invincible magical beasts being effortlessly defeated by Kalego and Balam once they decided to actually step in.
I am hoping this tone remains as the antagonists make their moves more- I don't want to see this devolve into most of the other shonen action series out there, where the kids are ten times stronger and more competent than the adults charged with instructing them. I think it would be kind of interesting of a direction for Baal to have completely miscalculated the scale of power concentrated in this academy that could oppose his efforts to overthrow society, having erroneously presumed the demons that haven't sworn to him have all grown weak and soft in this current era of the demon world.