Galatine

Galatine, the Holy Sword of the Sun, a blade that had been previously wielded by the fairy Vivien, known as the Lady of the Lake, and who had gifted it upon Gawain.

Summary
Galatine is said to have been a sword that had been forged within the sun and had descended upon the world, and found by its first wielder, Vivien, known as the Lady of the Lake, and a fairy appearing in Arthurian Legend, and was said to have been an enchantress. Galatine represents the rays of the heat from the sun, due to the pseudo-sun which is contained within its hilt, giving it the power to manipulate flames and due to its affinity for Light, those flames are transformed into that of Holy Flame.

Vivien passed the blade onto Gawain, one of the Knights of the Round Table, and after his death, the blade was acquired by the Church. Its wielders since then are unknown, however, after Valper Galilei had found the blade hidden within the Church, he had stolen it, sealing it within a pocket dimension, similar to how Xenovia keeps Durandal. It is believed that his theft of the Holy Sword played a part in his excommunication.

Appearance
The Holy Sword is a greatsword, with its entire length being around five feet to six feet. The entire body of the sword, from pommel to its point, is a darkened black in color, almost as if it is covered in soot. When activated, red flows through the blade, lighting it up as Holy Flames begin to run up and down its darkened steel, however, its user is unaffected by the red hot flame.

Abilities
Galatine, being a sword that is said to have come from the sun, produces red hot flames, that when combined with the Holy nature of the blade, allows the user to manipulate Holy Flame, which is also the signature move of Uriel. The flames are a deep red in color with a white outline that bites like a beast and burns like a furnace's flames.

The wielder of the blade is unaffected by its searing heat and flames.

Vivien
The Lady of the Lake and the first known wielder of the Holy Sword of the Sun. Not much is known about her use, other than how she kept it with her until she passed the sword down upon Gawain, a member of the Knights of the Round Table.

Gawain
A member of the Knights of the Round Table that had served under King Arthur. He was gifted this blade by the Lady of the Lake. He was known as one of the greatest knights and he was a close comrade to King Arthur Pendragon himself. He had been struck down by Mordred himself when he had betrayed King Arthur, his own father. After Gawain's death, Galatine fell into possession by the Church, who kept the blade safe and hidden for hundreds of years, until it was stolen by Valper Galilei.

Valper Galilei
An excommunicated priest of the Church, nicknamed "Genocide Archbishop" due to his experimentation in trying to draw out the ability to wield Holy Swords with children, before killing them through the use of poisonous gas. After being excommunicated, he joined the Grigori under Kokabiel and eventually perfected his method of creating what he dubbed "Crystallized Light", which he would later use on himself in order to use Holy Swords. Due to his theft of the Holy Sword of the Sun, he had his opportunity to wield a Holy Sword of his own, which he would then unseal and utilize against Kiba Yuuto when he achieved Balance Breaker of his Sacred Gear, [Sword Birth], known as [Sword of Betrayer].

Trivia

 * The blade's appearance is based off of the name of the same name from Warframe.