I've noticed that too, the rounding is generous. But I won't complain about it.

For other magic it seems to be :
Base damage(increase by level) * int mod * magic mod (pyro or warfare)

For physical it's :
Weapon dmg * (strength + weapon ability (2hand or ranged) ) * warfare
I'm not sure how huntsman adds from here.

Necromancy is the only magic worth taking. But it still does not compare (by far) to what a hunter can deal.
And some of the skill of necromancy need to have body around, or blood. But if you have a lot, it become insane with the source point skill.

I kinda want to play inquisitor, but having to split int and strength is meh.