Lower the drop rate for the minions. (Making it harder to receive said item) Currently there's so many armadyl pieces being spawned in due to minions that it's around 2m a piece. Now this could be because armadyl is rather inefficient as opposed to void. But these are still considered one of the best items in the game and should be treated as such in terms of DR.
You can camp armadyl for less then 20 minutes and come out with a drop every time.