Bloodthirsty Blade (Muramasa)

Weapon (shortsword), rare (requires attunement)

These +1 shortswords are said to have been crafted by a legendary smith from another world and age and often are referred to by his name: Muramasa.

These blades are reputed to possess an insatiable bloodlust, and they score a critical hit on a living creature on a 19 or 20, as long as that creature has blood. However, whenever the wielder makes an attack roll against a living creature with a bloodthirsty blade a curse is activated. Thereafter, the wielder cannot sheathe the bloodthirsty blade or attack with any other weapon until the wielder scores a critical hit against a living foe or reduces a living target below 0 hit points with the weapon.

Whenever the wielder scores a critical hit with a Muramasa against a living creature, they gain 2d6 temporary hit points, and they have advantage on Strength and Constitution checks for 10 minutes, though these bonuses end immediately if the wielder sheathes the Muramasa or attacks with a different weapon.