I want all of them... At some exhibition
Maybe once during the game progress do you get the chance to forge your own replica version of one of the items of your choosing, and a quest to grab and replace the real deal with your replica. After which security is raised, making it impossible to pull something similar off again. Maybe we can be able to steal a few items (based on weight check), but using them would be "illegal", and everyone would recognize and report you if you used such a weapon. Our choice - one item we can actually use (theft not detected), or many items none of which we can use (theft detected).
I don't want to find Umbra and use it, simply because my character has no relation to that weapon - I do, but not my character. For "normal artifacts", I want to explore something new. Create new legendary weapons that my character and I have no previous relation to. Fresh and inventive, not just recyclables.