It seems fine however death usually forces the noble phantasm into a sort of deactivation unless it's a curse. Likewise characters with some sort of skill like say bravery should be able to resist it.

I do have my reservations as it could end up crippling some servants however the masters, or servants in question should be able to go through some sort of luck check to resist the thing. Also the people in question would have needed to do something deplorable in life for it to even work.