I don't see why this shouldn't affect shields. You only get six of these maximum, that's six turns of enemy exposure assuming you live long enough to draw them all - and you neither deny your opponent any draws, nor do you actually destroy the shield. In fact, if you use it against Phase Shield, you have just given your opponent at least one counter back. It also makes sense conceptually - a strong enough gale to blow the enemy's shield out of his hand (and back into his hand, heh).