upgrade troop weapons

hear me out here, how about an extra upgrade slot for each character, the normal upgrade in laboratory and then the ability to upgrade them again with dark or gold, but this is a weapon increase, so they can change the weapons they use, like the barbs get a flaming sword that does fire damage that adds damage over time for a few seconds, archers can fire poison arrows that also do extra damage after the hit, damage over time like the flame thrower in boom beach? it could start from level 2 and that would mean they could get extra upgrades but if its with dark then the lower players would have to wait till they got dark elixer.