City artifacts
It would be nice if, when your champion is in a town, the Trade Screen allowed you to trade equipment to the town. You could leave equipment you are not using in a town where other champions could come and pick it up.
You could also build further on this idea by making some of the artifacts that you find in various quests be items that affect the city that they are placed in. You could also make the Wildlands trophies into such items and be able to move them if you wanted to.