Excalibur (エクスカリバー, Ekusukaribā?), differentiated from the Excalibur of Fate/stay night as Excalibur Proto: Sword of Promised Victory (約束された勝利の剣, Yakusokusareta Shōri no Ken?) in Hanafuda, is a Divine Construct and the golden holy sword of King Arthur. Differing from that of Saber's Excalibur, it is a double-sealed weapon locked by two seals, Invisible Air and Restraints of the Round Table.
If seven or more seals are released, the sword's true power as a Divine Construct to save the world is released, but otherwise, it still acts as a powerful Anti-Fortress Noble Phantasm. The seals remain locked until he activates it, causing a series of clanking sounds as the Restraints are lifted one by one. Activated to counter Enki, it releases as an expanding pillar of light that cleaves both the "Star of Destruction" and Archer with a single strike. Expanding larger than the city, it can even be witnessed from space.
Even without releasing its true name, Excalibur is still able to release its slash of light that varies in strength but are all weaker than its Anti-Fortress attack; however, it can be further enhanced in its destructive power by his Mana Burst Skill. One was powerful enough to counter the Sword of Paracelsus Noble Phantasm attack, while another overrided its power snatching ability. With six Restraints released, Excalibur's Anti-Fortress attack was powerful enough to defeat the rampaging Beast after the death of Manaka Sajyou.
- ↑ Fate/Prototype: Fragments of Blue and Silver - Volume 5: Whether it is a battle to use the Holy Sword of the planet, the Divine Construct to save the world...Holy Sword, 6 restraints released! Unfortunately, a majority was unable to be reached. A perfect release of the True Name is unable to be realized. Even so, light emits. An Anti-Fortress Noble Phantasm with domineering strength...
- ↑ Fate/Prototype: Fragments of Blue and Silver: Arc 5, Act 5, Part 3-D, translated by PhoenixRising at Beast's Lair.
- ↑ Fate/Prototype: Fragments of Blue and Silver: Arc 5, Final Act, Part 3-D, translated by PhoenixRising at Beast's Lair.