Shortsword of Wounding

(Requires Attunement)
Hit points lost to this weapon can't be regained.
Once per turn when you hit a creature with an
attack using this weapon, you can wound the
target. At the start the creatures turn, it takes 1d4 necrotic damage for each time you've wounded it
then make a DC 15 Constitution saving throw to
end the wound's effect. Alternatively the creature
can use an action to make a make a DC 15
Medicine check to end the wound's effect.