Descent: Can you get rid of cursed items?
I don't recall there being any rules for auto-equipping cursed items; you can elect to use it if you want to, but you don't have to.

You get a curse token for equipping a cursed item, and while you can remove the cursed item as normal, you do not lose the curse token for un-equipping the item (so if you re-equip it later, you get another curse token).

In your example, if the mage can simply choose not to equip the weapon.

Now, Dark Relics, on the other hand, must be equipped when found, and the only normal way to remove them is to die.  Fun fun...