Back to what Owen said down below. By what it seems the "gods" hand out 3 abilities for free then they can learn others. It states that they give abilities but not that there is a max.
For example mage lady says they want to be no.1 mage in general instead of stating they want to be a specific...
ok so there being multiple ghosts/Spirits (if they is a difference)
That would suggest that they had and killed lovers or "took a part of them" when they broke up
They state that while healers can heal it can only be in small amounts, he seems to have strong healing (sword straight through chest) only because he got that juice that makes him OP