«Lambent Light» (ランベントライト, Ranbento Raito?) was a one-handed rapier owned by Asuna in Sword Art Online (SAO). The rapier was crafted by Lisbeth as a masterpiece of a quality that she could only achieve once every three months. Asuna's rapier, combined with her speed, earned her the nickname «The Flash». The Lambent Light was boosted to +32 by Lisbeth and was Asuna's final weapon in Sword Art Online.
On June 24, 2024, Asuna brought the Lambent Light to Lisbeth to be sharpened for her meeting with Kirito later that day.
On October 18, 2024, Asuna employed the Lambent Light during monster encounters throughout her and Kirito's exploration of the 74th Floor Labyrinth. She was forced to use it against The Gleam Eyes to protect an Aincrad Liberation Force party from being decimated by the Floor Boss. Five days later on October 23, the Flash utilized the blade to quickly and viciously attack Kuradeel, after the latter killed Godfree, along with another member of the Knights of the Blood, and nearly killed Kirito, but she was disarmed when she hesitated to deal the final blow.
On November 7, 2024, after the Dark Repulser was shattered and Kirito was disarmed of the Elucidator, the rapier was used by the swordsman to stab and defeat Heathcliff in the final battle, thus clearing the game.
On April 29, 2026, during the battle in the Ruby Palace, the Lambent Light was loaded with the rest of the save data for Asuna's equipment from the SAO server by Yui. The rapier was used by Asuna to perform Mother's Rosario on An Incarnation of the Radius as one of the final attacks on the boss.