The Night Sword is a Vampire Survivors weapon that got added along with the Legacy of the Moonspell DLC. It’s a solid weapon that also has a chance of healing the user. Once it evolves, it becomes the Murasama, a sword with higher damage and more chance to generate hearts.
Night Sword’s Evolution Condition
Like all other weapons in Vampire Survivors, the Night Sword needs a passive item for it to evolve. Unlike other weapons, however, both the weapon and the passive item needs to be at max level.
The passive item needed for the Night Sword is the Stone Mask, a passive item that increases your Greed by 10%. You unlock the Stone Mask by finding it first in the Inlaid Library.
Once the Night Sword and the Stone Mask are equipped and both are at max level, open a chest that’s dropped by bigger and more powerful enemies. They usually spawn at each level after the 10-minute mark. This completes the evolution.
The Muramasa has similar functions to the Night Sword. The clear difference is that it now has bigger projectiles and the cooldown is vastly lower. The Muramasa also deals more damage. Its fast attacks and high damage allows it to kill enemies more easily, thus generating more hearts.
The small caveat of the Muramasa is that it slowly drains the user’s HP. However, given the abundance of enemies and how often you’ll be regenerating HP because of the weapon’s life-stealing capabilities, this is barely a problem at all.