The Warden cache you find in Denerim, is considered the last of the Grey Warden's inventory after Loghain closed the Compound in the palace. It would make sense for a group of accomplished warriors such as the Grey Wardens to have an armoury of their own, in said compound. I do believe that Bioware intended (but didn't really implement) to have the Grey Wardens have a standardised armour, like they do in Dragon Age 2, which of course would need to go [i]somewhere[/i] when not being worn, ect.