When you first attune to this item and at each dawn after that, choose a magical bonus of +1 to +3. This sword gains that bonus to its attack and damage rolls.
For each point of bonus you choose for the sword, you gain vulnerability to 1 type of weapon damage (bludgeoning, piercing, or slashing—chosen at random from the types you are not already vulnerable to) and 1 type of other damage (acid, cold, fire, force, lightning, necrotic, poison, psychic, radiant, and thunder—also chosen at random from the types you are not already vulnerable to).
Whether you change the bonus or not, the damage types you are vulnerable to are randomly selected again at dawn.
Curse. This weapon is cursed, and becoming attuned to it extends the curse to you. Until the curse is broken with a remove curse spell or similar magic, you are unwilling to part with the weapon.