You can buy all these truly strange spells from NPCs. Weakness to Disease, Resist Corprus, Cure Paralysis on Self...And im just wondering, whats up with that? It kinda feels like these are remnants, remnants from some game that Morrowind was going to be, but never was. So Im just wondering if anyone has insight on this. It wouldnt be odd if you could only *make* them. The fact that you buy named spells from NPCs with those effects is what confuses the hell out of me. Is there a beta thing for it like the Oblivion demo videos?

As far as I know:

-Weakness to Disease can be used on self to be infected more easily by vampires/werewolves.
-Resist Corprus is useless. That one really is a remain of an old concept that didn't reach the final version.
-Cure paralysis can be very useful once you use the spellmaker to create an OnTouch version. No more paralyzed companions!

Cure paralysis on self is like a middle finger.

Resist Corprus makes sense from a flavour point of view even though it's useless to the player. Corprus is a big problem on the island so it makes sense that people will try to find a way to resist it even if finding ways to cure it isn't working. Not everyone on Vvardenfell is immune to corprus like the player is, at least storywise.

Resist Corprus is also handy for roleplay. The PC doesn't know s/he (or anyone else, for that matter) can't contract corprus except as dictated by the game, therefore it makes no sense to behave as if immunity is a given. So as useless as the spell is, I nonetheless have my character cast it on herself (and her companions) when the circumstance arises.