Abilities are actually added to your Spells list, in addition to the active effect entry. RefScope should show that.
I checked the spells and couldn't see any dispel spell besides the couple of dispel spells my char has bought/made. So can't find any corresponding spell.
It's not an a ability its a "buff" or a permanent enchantment, it might be a reward from a quest or it might be a glitch that you can get from quest items when your character gets completely stripped of his items thus the quest item stays but unequiped which results in having a permanent.
Can you tell us since when do you have this dispel enchantment on yourself?
I wonder if it's connected to KotN? My char is under the Damage Fatigue effect from the Curse of the Consumed part of the KotN questline. That's the only thing I can think of.
I'll load some earlier saves and check.