The control DC is wisdom based, but how many times you can assert control per day is equal to your Cha modifier. It's weird. In any case, I'll have to look into that unseelie fey business.
Aura of Despair, of course. It even has the same range as the passive infect.
As for the Hexblade levels, you're referring to use of the Dark Companion ACF, right? That one is visible, so it wouldn't work in a stealth situation. Unless it's possible to make illusion effects that are not spells invisible... that might be worth looking into as well.
Folocor's aura of sadness should work, so long as we don't think too hard about the mechanics of standing adjacent to a disease. Disease Form's wording is excruciatingly vague for how radical a departure from the normal rules it involves, so for our purposes let's continue on the assumption the character occupies the same 5-foot space as when materialized, and measure distances from there.
Thank you all for the replies.
Edit: Ah, you mean the Hexblade's curse ability itself. For some reason I had thought it was touch based, but a 60ft range should work.