You have some sort of strange or mystical source of your power, somewhat like a Supernatural Creature. This can be an item, a ritual you perform repeatedly, a secret your enemies must not get to know or even a physical attribute, such as your long hair.
If you lose your connection to this power origin, you get a -5 penalty to your best skill and to your highest attribute. If several skills/attributes arr equal, this should be your "signature" abilities, the ones that make you into who you are.
The cure is of course to restore your connection.