Death Well Pendant
It looks like a pendant with a silver ornamental glass box, containing a glowing crystal inside.
While wearing it and attuned, when the wearer kills a creature, they can expand a charge to attempt to fear the creatures 5ft. around the slayed entity, being feared on a failed Wisdom Save (DC 18).
We got this item after killing a Valkyrie in session 63 - Wondering at the Citadel.
Object type: Pendant
Charge(s): Proficiency Bonus times per day
Attunement: Yes
Curse: The wearer feels a overwhelming sense of grief when wearing the pendant.