Non Steam Player - Buys Guardian Pack and the server gets the ok to give said player the items.
Steam Player - Buys Guardian Pack and then clicks on the game name in the steam library. Then "downloads" something. Activating the "DLC" gives the server the ok to give the player the items.
Is there really any difference in the long run besides being able to trade the "DLC" on steam?
Steam users can gift (or re-sell) the DLC since it's a.... DLC.
Non-steam users can't use such feature, they buy the pack for themselves only.
Does that balance it out?
I's steam's way of handling DLCs anyways. Don't blame it entirely on the game.