Death Knell
This dark metal weapon is grimly ornate. You gain a +2 bonus to attack and damage rolls made with this magic weapon. Once per turn when you reduce a Small or larger creature to 0 hit points with this weapon, a foreboding, gong-like sound emanates from the blade. When this happens, any hostile creature within 15 feet of the target that’s missing any of its hit points must make a DC 15 Wisdom saving throw. On a failed save, a creature takes 1d8 psychic damage, or half as much damage on a successful one.
"Death called for you: how kind of you to answer," said the man. The sound of a rumbling bell filled his chest and the alleyway around him. He pulled the blade free of the bandit's chest with a sickening squelch before turning his gaze back to the others. Several were clutching their heads and grimacing, suffering from a pain that only they could perceive. "Ahh, that's it. I can hear it calling for you, and you, and you, too, now. So tell me, which of you will answer it first, I wonder?"