That's why it would be an over shield, like halo. When the shield is gone, so is the the damage multiplier. You could link it with a trap grenade that can slow and/or stop a player in their tracks and rend their Armor useless, much like a bear trap with the effect of Thorn. And the melee could be a throwable bola that causes slowness like the Wizards poison or a "zero G" state for a few seconds. Also, throw in somewhere an ability to wall hang for a small amount of time. I do apologize if any of this was someone else's ideas, I just rattled off what I was thinking.