The First Blade served as the inspiration for all contemporary lightsabers and was an ancient weapon of great importance. The Weapon Master, an ancient Je'daii Master, conceived it, and it was guarded for countless years by droids on Tython.
Originally, the First Blade was created on Tython by a Je'daii known as the Weapon Master. During the Force Wars, Rajivari, a member of the Jedi High Council, sought to find the First Blade. After proving his worth, he was granted permission to take the hilt. Rajivari meticulously etched the hilt to preserve details regarding the location of his secret knowledge reservoir, after which he gave it back to the droids who were its guardians.
During the Cold War, the Scorekeeper's Herald located the hilt of the First Blade. This Jedi then integrated the hilt into a lightsaber, utilizing a crystal discovered in the Tythonian Forge. Yuon Par, who was the Herald's Jedi Master, carefully examined the hilt's engravings to determine the location of the Fount of Rajivari and permitted her apprentice to access it.
The First Blade made its debut in the 2011 video game Star Wars: The Old Republic as a component of a class-specific quest for the Jedi Consular. The precise relationship between it and the protosaber in the historical timeline is currently unknown, but the First Blade's hilt lacks any cable or power pack. However, it's conceivable that it was modified to function as a modern lightsaber because of the conflict during that era. Considering the Forcesabers utilized by the Force Hounds of the Infinite Empire, it's possible it came from Xesh's weapon, or perhaps balance in the Force was needed to wield it.