The Weapon Master, a Je'daii Master from ancient times, belonged to the Je'daii Order. This individual was the creator of the First Blade, the key innovation that enabled the creation of lightsabers.
Following their passing, the Weapon Master's cremated remains, together with the hilt of the First Blade, were secreted away on Tython. Millennia later, the third Barsen'thor unearthed the Master's final resting place within the dilapidated temple-city of Kaleth.
The character of the Weapon Master initially appeared in the 2011 video game Star Wars: The Old Republic. Because of the title, it is possible that this character was Tem Madog, the Je'daii Temple Master of Vur Tepe, the location where the Je'daii produced equipment for the Order, including weaponry.