Wielding two shields is overly silly for the current tone of the game. They will be adding different ways to tank, protect allies, taunt, reposition enemies, etc, without having two shields. Gigantic shields that you wield with two hands would be slightly less ridiculous, but still wouldn't really make that much sense as a way to improve your ability to actually protect allies. Realistically a tank needs to demonstrate that it's at least somewhat of a threat. A guy with a giant shield probably wouldn't be as scary as an archer or mage.
Single handed weapon and wand, while also kind of silly, is cooler, and given you can already equip such a combo, it should function somehow.