The tip about Gravity was just "bring multiple Gravity potions" because that's how you disrupt one of the analyses; while it's not as powerful against Yg'Xel, it can be used multiple times against him.
Observe Attack Vectors should be giving Yg'Xel Analysis points when he's hit, but I just realized he didn't even get the Analysis state that runs everything! I thought for sure he had it.
I'll go ahead and release a patch with this and the NPCs fixed.