How about this? Make the minimum weight 5 lbs, to eliminate all of the small stuff and add the following to the end:
Special: If a weapon is used as ammunition for this power, treat the wielder as being not proficient with that weapon. A weapon used with this power can deal no more damage when thrown with the gauntlets than if used in melee combat. Treat bows, crossbows, and other ranged weapons that require ammunition to be used, as improvised weapons for purposes of calculating damage for this power.
Adding that to the end means that you can't take a weapon and get 2d6 damage out of it (if it doesn't already deal that much damage) and eliminates the menial-weight-item-throwing-for-massive-damage problem.