Nico's sword is a three-foot-long black sword forged from Stygian iron that has the power to suck away its victim's essence. Nico di Angelo acquired it sometime between The Titan's Curse and The Battle of the Labyrinth. The origin of the sword is currently unknown, but there is a possibility that Nico forged it himself in The Battle of the Labyrinth when he is seen in a camp ground near the River Styx.
In The Son of Neptune, Hazel mentions that she at first didn't think much of it.
In The Mark of Athena, Hazel Levesque uses her sense of Underworld metals to try and track down her brother who has been captured by the giants. Unfortunately, Gaea separated Nico and his sword to lead his friends attempting to rescue him into a trap.
Percy Jackson describes it as being, "black as a nightmare and truly frightening."
- Nico uses it to summon as well as banish the dead by stabbing it into the ground.
- The sword sucks the essence of the killed monster into the sword, so the monster stays in Tartarus longer.
- The sword strikes fear into its owner's enemies.
- The sword seems to "make shadows even gloomier, as if the infernal metal was soaking the light and heat out of the air", according to Jason Grace.
- It is unknown whether the sword itself has necromancy, or Nico simply uses it as a means of channeling his power.
|Personal Weapons:||Riptide | Annabeth's Knife | Backbiter | Frank's Spear | Hazel's Spatha | Katoptris | Nico's Sword | Thalia's Spear | Aegis | Maimer | Kronos' Scythe | Ivlivs | Master Bolt | Poseidon's Trident | Sword of Hades | Reyna's Spear | Hades' Staff | Juno's Gladius | Annabeth's Sword|
|Magical Items:||Annabeth's Yankees Cap | Helm of Darkness | Keys of Hades | Flying Chariot | Golden Apple | Greek Fire | Hermes' Multivitamins | Leo's Magical Toolbelt | Nectar and Ambrosia | Pandora's Pithos | Winged Shoes | The Golden Fleece | Stygian Ice Whistle | Serapis' Staff|
|Spoils of War:||The Minotaur's Horn | Medusa's Head | Kampê's Scimitars | Nemean Lion's Pelt | Gorgon Blood | Cornucopia|
|Items:||Camp Necklace | Chameleon Armor | Daedalus' Laptop | Golden drachma | Denarius | Mark of Athena | The Pax | Video Shield | Wristwatch Shield | Golden Mango | Sibylline Books|
|Blessed Metals:||Celestial Bronze | Imperial Gold | Stygian Iron|