Great
I realize it's sort of hard to understand it - I myself had some trougbles grasping it. The general rule of thumb is:
Heroes (Warrior, Paladin, Mage) have skills
Units have abilities and some may cause post-effects (burning, poisoning)
Spells have (or don't have) effects
This is how I remembered the terms
And please read the explanation in the other topic, because this is NOT A BUG.