True, true. I can see a problem with that though - mages wearing two shields. To avoid abuse, forcing mages to keep one hand free when casting spells is the only way to go. The relative freedom of holding a weapon should, of course, be available (can't have mages without staves can we?) but dual shields is just a big no-no for your average sorceror. Dual shields could otherwise be a good idea. Like if you've got a mission to escort someone through hostile areas, then it might be a good idea to keep this person well-defended, especially if he/she doesn't have much to come up with in a close fight.