You looking at the Diseased Ratskin Mask and thinking, why does wearing something like this raise your charasima?
Remember how parentheses work in algebra? Instead of looking at it like this:
Diseased( Ratskin ) Mask
Look at it like this:
( Diseased Rat)skin Mask
So it wasn't the skin, but the rat, that was diseased. Maybe he had colon cancer? By wearing the skin of a rat who wasn't killed for this mask, you are supporting the fight against killing animals just to wear their skins. This shows efficiency/economics/compassion/whatever. Or, you've just got a sick rat fetish. However, the arguement is there for the CHA :)