I am no expert and I may well be wrong about this, but here is my understanding. I welcome corrections. Think of eater and killer as suffixes in WOTV. Eater means a percent of the damage heals you so, yes it could be thought of as damage reduction. But if you get over 50, you will actually gain life if "damaged" by that type of attack. Man eater works on any attack from a human, light eater works on light damage, etc. Killer increases damage against that type of unit.