Murderer's Knot

This black strand of leather is tied to look like a peace knot when the weapon is worn, but it doesn't hamper drawing the weapon. When you activate the knot, the creature you damaged takes 1d6 bleed damage and is off-guard until the bleed ends.

If you have the Twist the Knife feat, the talisman instead deals persistent bleed damage equal to your sneak attack damage.