If you play without Summoning, then I don't see much point in Lucretia, because Magic becomes practically useless.
I'll say right away, this is just my opinion (IMHO) about the usefulness of Magic for a Necromancer; we can argue about it in another thread (I personally only take it for the Town Portal spell).
Major Whirlwind
"I would like to remind you that people are people; they are neither evil nor good."
I agree! However, I'm not talking about PEOPLE in general, but about the HOLY EMPIRE OF GRIFFON. After all, Markel, Arantir, Zoltan, Ravena, and Ornela, despite being Necromancers, are also people. Plus, some mages from the Silver Cities.
Yes, by the way, about "good" and "bad." For example, I don't directly associate Light with "good" (see the icon of Righteous Wrath). And in life, I wouldn't want to meet some Inquisitor any more than a Demon. But that same Inquisitor doesn't really fit in my head with Tmo. So, in my opinion, you're wrong here – ideology is one thing, and the type of magic is something completely different.
As for the situation, it's not that rare: a deep late game, Lucretia, and castles with Light spells can be "set up" this way.