Glimmer for weapon parts. Or armor materials for weapon parts. Or bring a crap load of spin metal to the gunsmith and he ships it off to a foundry to be melted down and turned into weapon parts that are then waiting for you on the next Armsday. Or they could just fix the drop ratio of weapons to armor. Armor drops easily 10:1 ratio to weapons. And then nearly two thirds of those weapons turn into motes at the cryptarch. That's ridiculous. Just fix the ratio of armor to weapons and have armor turn into motes a little more often and weapons a little less.