In Requiem for the Phantom (episode 3, ~6:30), the Scythe Master puts some kind of oil or lube on Ein's body. Why would he put lube on her body?
It is symbolic. In this scene, he is cleaning his weapons. In Gusseppie's mind, Ein is not human, she is a weapon. An inanimate object, and in the same way he cares for is ruger, he cares for Ein. While I don't think he was literally rubbing her down in weapons lubricant or copper solvent, I believe the intent was the same.