Shields are being debated like mad amongst the Rattrap crowd right now. I like your solution because you're right--it does seem like it's something that makes Cap less likely to be hit, rather than just protection. But +2 or +3 to Dodge is pretty hefty as far as a bonus goes. I think I'd make it +2 to DG for the purposes of defending against gunfire only, make it throwable like an Improvised Weapon, and make it cost 2 Attribute Points to purchase.
Is what I would do.