It protects against spell damage, too.
Maybe you could desing a "damage spell blocker" around it.
I once watched the arena fights and saw a fight between marignon and someone else. I can't remember who it was but he'd sent some nasty mage to the arena while Marignon only sent a Chartmaker.
So I thought the chartmaker was toast but still I watched.
In the first round the chartmaker cast Twist Fate and the other mage a damage spell.
So I though with his protection gone the chartmaker should be dead soon but he just cast Twist Fate again. And the other mage wasted another spell and like this it went on for some more rounds until the enemy mage passed out from fatigue.
The chartmaker just stepped up and killed him with the sword.
