Currently the mod replaces the Necrotic modifier from the necrotic bone with the parasitic modifier, which doesn't work on tools.
Please try to work this out, since it makes my weapons less useful

Huh, weird. I don't know why this would affect only this modifier and not the other ones. Anyway, I'll get this fixed.

After working through this for a while, I've realized that the Tinkers system wasn't really built to accommodate multiple modifiers attached to a single item. I'm trying to figure out a workaround, but worst case scenario is that I'll have to make brand new items to house all of the armor modifiers.