That's an awesome subtle detail, been thinking something was off about that locket in passing... But you nailed it! 
Should be wearable by player have some buff to make a bit harder to part with, or at least a choice to be made. Sort of like molerat cure or Mysterious serum quest item.
i.e. Do you go for the "Abernathy Discount"/workshop access or keep it a while for a rad resist/stealth/charisma boost, or some such thing?
The other in-game lockets do nothing either, (which also doesn't really make any sense).
Should be very simple (I almost know how to do it):
1) Thing to do is make custom armor piece out of one.
2) Then apply/hook at quest end trigger where discount is applied.
3) Something, something...
4) Profit .
PM me if this gets made by someone more capable than my own damn self.
Edited by Blinxys, 08 July 2022 - 08:53 PM.