Jedi Master Kol Skywalker built his blue-bladed lightsaber prior to the failure of the Ossus Project in 127 ABY. Kol wielded it in combat against Darth Nihl and the rest of the Sith strike force that attacked Ossus in 130 ABY. It was lost after Kol's death and later discovered by Yuuzhan Vong Master Shaper Nei Rin amongst the ruins. Rin had replaced the original focusing crystal with a lambent crystal of her own shaping after it was badly burnt in the battle against the Sith, thus the blue blade was replaced with a green blade.
Seven years later when Kol's son, Cade Skywalker, discovered the Hidden Temple, Nei Rin gifted him the lightsaber. Cade carried the weapon with him during his mission on Coruscant to rescue Jedi healer Hosk Trey'lis where it was temporarily seized and encased in a transparisteel case, by Darth Krayt, to honor Cade's father. Cade was able to recover the weapon before his escape and carried it with him in his battles with the Sith up until the death of Darth Krayt. As of 138 ABY it was still believed to be in his possession.