Excalibur

Summary
The Excalibur is one of the two Holy Swords wielded by The Legendary King, King Arthur Pendragon, of Camelot. According to Allen and Yuri, the Excalibur is a holy weapon that was created through means of magic, witchcraft and alchemy by those who reached the territory of God. At some point, the original Excalibur was broken, and the pieces were made into twelve different swords with the name "Excalibur" in them and two of the blades were each stored by the Catholic Church, Protestant Church of England, and the Eastern Orthodox Church. Valper Galilei, known as the "Genocide Archbishop", previously did human experiments to find people who were capable of using the pieces of Excalibur, and disposed those who were not able of doing so. Arthur Pendragon was one of the people involved in the experiments, which caused him to grow a deep hatred towards the Excaliburs and anyone related to it. It is later revealed that the Holy Project was a success, however there was a requirement to wield the Holy Swords: the candidate must have a mass property of light attribute in their body. Therefore, Valper removed the light property from candidates to transfer the necessary element to someone that had the capacity of wielding a Holy Sword. However, this transfer resulted in the deaths of the donors. Due to this, he was excommunicated from the Church.

The Fallen Angel Samael led his men into stealing an Excalibur from each Church under the intention of starting another Holy War. Samael later defeats Irina and took her Excalibur Mimic, and orders Valper to fuse the four Excaliburs into one. However, after Elly and Arthur broke the Fused Excalibur, Irina takes the remaining pieces of the Excaliburs, along with Elly's Excalibur Crater, back to the Church to be reforged. Elly states that a method to artificially produce light attribute without having to harvest it from people has been developed, allowing for the creation of more Holy Sword wielders.

As of the Violet Tokyo Arc, Excalibur Crater and Demon Sword Gram are fused into the Durandal where the swords function as a form of sheath to help control the Durandal.

True Excalibur
The original Excalibur sword wielded by King Arthur before it broke. It is a sword that rivaled that of Durandal. The sword has wide range of versatile capabilities such as shape-shifting, invisibility, subjugation, illusions, control and create ice, fire and wind, a massive amount of destructive force and granting the wielder enhanced speed and strength. After it broke, the Excalibur was reforged into twelve swords through alchemy and witchcraft, each one possessing one of True Excalibur's different abilities. The swords eventually came to be known as the Excalibur's Twelve Spawns. When the twelve swords come together, True Excalibur has access to all of its original abilities.

Excalibur's Twelve Spawns
Excalibur Crater: Also known as Calibur Meteor Impactor, is a sword with the ability to unleash a wave of pure destructive power that can easily shatter anything it comes into contact with, leaving nothing but a large crater in the ground.

Excalibur Mimic: Also known as Calibur Jester's Mimicry, is a sword which has the ability to transform itself into any shape as its wielder's desires (for example, in Irina's hands, it becomes a katana; and in Arthur's Hands, it becomes an broadsword).

Excalibur Rapid: Also known as Calibur Scatter Rapid, is a sword that grants both the wielder and the blade enhanced speed.

Excalibur Anti-Dream: Also known as Calibur Rival Dream Eater, is a sword that allows the wielder to cast illusions and manipulate dreams and nightmares.

Excalibur Transparency: Also known as Calibur Transparent, is a sword that allows the blade and its wielder to become invisible.

Excalibur Control: Also known as the Calibur Dominated Ruler, is a sword that grants the wielder the ability to control all things that he or she wishes. It is the strongest Excalibur fragment. It was wielded by Ban Ishiyama who used it to control Fenrir, before being ceded to Irina.

Excalibur Ulterior: Also known as Calibur Magic Ulterior Seal, an Excalibur that can seal magic and cannot cut physical objects. It just becomes intangible when slicing into objects.

Excalibur Ice: Also known as Calibur Sub-zero Ruler, an Excalibur with a blade made of ice that can create huge pillars of ice from the ground.

Excalibur Inferno: Also known as Calibur Engulfed Sun, an Excalibur with a blade made of fire.

Excalibur Whirlwind: Also known as Calibur Aeromancey, an Excalibur with the ability to control Wind, and create powerful whirlwinds, typhoons and hurricanes.

Excalibur Sting: Also known as Calibur Shatter Sting, is a sword that grants both the wielder and the blade enhanced strength.

Excalibur Solution: Also known as Calibur Destroyer Solution,  is a Sword that specialises in destruction.