That's a Freetime feature, sugoisma. It indicates that the sim has a high literature enthusiasm.
Since Maxis didn't make very many things sex-linked, my guess is that something specific to your game or to your individual high warlocks is causing their problem. I've never had the game generate a male witch yet, though, so I'm not the best judge.
I have this mod and my witchers can summon their spectral cats with no problems, just a slight delay...
I think we had a discussion a while back about this where several people using the mod had witches who could summon spectral cats and several people also using the mod had witches who could not. Or was that about roaches?
For the record, I've got the mod and my witches fail at summoning their cats.