Excalibur

Excalibur: Sword of Promised Victory (約束された勝利の剣（エクスカリバー)) is the strongest and most majestic holy sword that symbolizes King Arthur. It is her greatest and most powerful Noble Phantasm, which is a divine construction, the pinnacle of holy swords, forged by the planet as the crystallization of the wishes of mankind stored and tempered within the planet. It is the crystallization of the prayer named "glory" and everything etched in the hearts of those who are scattered at the sword's radiance; the nostalgic, sorrowful, and exalted dream of those who were placed on the bloody hell called a battlefield, of all warriors past, present, and future fully exposed to the fear of death and despair, and whom still cling to a desire: "to be exalted." It is one of the ultimate god-forged weapons, a Last Phantasm, which was guarded by extensions of the planet, Fairies, before briefly being passed on to Arturia by the Lady of the Lake and later returned to the lake before her death. It replaced the destroyed Caliburn, and its sheath, Avalon, provided partial immortality for its wielder. She eventually lost Avalon, and replaced it with Invisible Air, which she uses during the Holy Grail Wars to hide the sword and her identity. While it takes time to figure out the Noble Phantasms and identities of other Servants, Lancer is able to deduce her as King Arthur from only a glance, claiming that any Heroic Spirit that has traversed time and space to join the Holy Grail War will never mistake her golden sword for any other. It is a typical western sword with a length of ninety centimeters and a width of twelve centimeters, and it has Fairy Letters inscribed on it to show that it was not the work of mankind.

Excalibur is a weapon of directive energy that converts the prana of the wielder into light, intensifying the kinetic energy by convergence and acceleration, allowing for the use of Divine Spirit level thaumaturgy. It is an "ultimate killing technique" that releases light holding energy equaling Arturia's total amount of prana from the tip of the blade once the sword is swung. While the result is what looks like a large band of light, only the tip of the attack, which is a wave of light that can mow through the surface of the Earth, is capable of doing damage, as the band of light is the result of the "dislocation" of everything the attack destroys in its path. Its speed and power are among the greatest compared to other Noble Phantasms, and only Ea outmatches it on the point of pure power. Its prana consumption is extremely high, and it cannot be fired consecutively. When used while weakened by her connection with Shirou, she can only fire it once before she is almost out of energy, and when she tries to use it again even after restoring some energy in Night Without Dawn bad ending, she fails to even scratch Berserker due to the lack of prana and instantly fades away. Once Avalon is returned to her in Fate, she is able to use it a number of times in succession before fading away.

It ranks as an anti-fortress Noble Phantasm due to its magnitude and destructive power. Its concentric area of impact is broad enough to incinerate an entire military cohort, turn the ground into scorched earth and leave a great disorder in land that would never fade, cut into the clouds, and completely destroy the large creature summoned by Caster that can regenerate instantly after receiving mountain shattering attacks. Both hands are needed to use the attack, so losing access to her hands means being unable to use the ability. After the tendons in her left hand being damaged by Gae Buidhe makes it impossible to move her thumb or exert enough strength to grip the sword hilt, it is reflected upon changing Excalibur's status to an Anti-Unit Noble Phantasm with a range of 2-3 and a maximum target of one person. Its destructive power can also be a negative trait that limits its usage, as it can easily damage the surrounding area and kill a large number of people if used under the wrong conditions. It makes it impossible for her to use it against Archer during Fate/hollow ataraxia due to the great risk of destroying the Center Building and numerous buildings around it to reach him. Even while holding back energy to restrict damage to a minimum, it is still easily capable of completely destroying Fuyuki's church. It is also unable to be used against opponents who fight at an extremely close range, such as Assassin, who could cut off her head with Tsubame Gaeshi the instant she began to gather the energy in her sword.

Excalibur Morgan
Excalibur Morgan: Sword of Promised Victory (約束された勝利の剣（エクスカリバー・モルガン）), as it is called in Fate/unlimited codes, is the form Excalibur takes after Saber becomes "Saber Alter" due to the corruption caused by Angra Mainyu inside the Grail. Just as Morgana and Vivian, the fairies of the Lake, can coexist, Excalibur can also hold a dual existence of good and evil. Excalibur, as an amplifier of its owner's prana, also changes to reflect the change in Saber's inner feelings and corrupted nature. Becoming the "Black Sword of Ultimate Light", it is no longer sheathed in Invisible Air and takes on a different look. Rather than creating an almighty slash at the tip of the sword, Excalibur gathers a large amount of prana to cover the sword in a black light with the same shape. Holding the "black sun" in her hands, it can either used to attack using a blazing black flame in a similar fashion to the regular Excalibur, or as shown in unlimited codes, Saber can swing the mass of magical energy like a regular sword in an upward arc multiple times in succession with a technique named Vortigern: Hammer of the Vile King (卑王鉄槌（ヴォーティガーン）). Due to the corruption and the enormous amount of prana received from Sakura, Saber can fire this version of Excalibur without limit.