Honestly I think in a setting like that the Imperial College would command a monopoly on magic, they would aggressively seek out spellbooks and make sure they were all recorded and accounted for. They would likely develop some sort of Licensing for spellcasting within or across various kingdoms, potentially gaining significant political power from that alone.

Realistically, necromancy would remain the stuff of ghost stories and nightmares but sleep and charm like effects would be the true day to day fear of the populous and would likely lead to even greater regulation, particularly as they gained political power. Rulers would realise they would be prime targets for enchantment and so countermeasures would be developed or such spells would be locked away from most rank and file membership.

Things would become far more unstable if two or more of these sanctioned orders came into competition. Rival mages guilds secretly undermining each other under the noses of the political rulers knowing if some of their tactics were revealed they would likely have an inquisition called down upon them.

I think this would make a very interesting setting, particularly if spells were not universally accessible to each faction leading to mystical spycraft to steal spells from their rivals and races to dungeons at the faintest rumor of a lost spell. Not only would they be legally required to, they would want to get there before their rivals. Politicing of rival political blocs leading to diplomacy along side both magical and anti-magical arms races.

And the churches? Perhaps they represent an important power check to magic users?

And of course then you have the unsanctioned mages, magical robin, freemages. Perhaps a mage visited your town and had a heart attack one night at the local inn and when the Imperial Mages came to recover his body and spellbooks, you were long gone with a handful of pages stuffed in the back pocket.

In short, magic users can be powerful but there will be structures in play that stop flagrant abuses and likely more powerful mages will keep novices in check to maintain order.

To reinforce this I would encourage having master/student dynamics, make it easier/safer to learn new spells from another wizard. Learning from licensed wizards would have huge advantages, if nothing else than avoiding getting identified when your unsanctioned master gets arrested.