My idea for a trading system is that you (Bungie) could make it so that we can only trade with someone close to or at our level, and we both have to put in an item OF THE SAME RARITY. This avoids level 20 or higher players giving low level players legendaries or exotics. For example, I like using scout rifles, and my friend likes using auto rifles, and when we finished a strike, I got a nice rare auto rifle and he got a nice rare scout rifle, and there was nothing we could do about it. But if you implemented this, there would be no trading of legendaries to low level players, and friends could exchange loot.