[quote=@Lugubrious]
The Artifact: (What items are so dangerous to possess that someone wouldn't dare speak of them to authority?) a collar once used for human enslavement by a maniacal mage of days now past.  The heroes who defeated the madman were able to damage the collar, but not fully destroy it, and the collar is a central thematic piece of the legends surrounding the madman, and is demonized along with him.
[/quote]

Not a bad idea but this also has to be the magic that damages the binding spell on the main characters powers. While a slave crown (to quote Final Fantasy XI) would be both an interesting idea to toy with and something to be kept out of the king's hands I don't see how it would be able to do damage to another kind of enchantment.