The moldering shards might be bugged. I have read reports on Reddit as well as heard from friends that sometimes it will get applied to someone else in the fireteam. For instance; one particular player had been farming for hadium and turning them in to Eris for moldering shards until he had about 40 of them. When his team beat Oryx another player received weapons and armor who had about 15 shards while he received the lesser rewards (legendary class item). 20 moldering shards were removed from his inventory. It isn't certain but it looks like there might be a glitch.