[Source] The lightsaber of Jedi Knight Exar Kun was a device that was initially created to produce a single beam of blue-white energy. However, upon his ascension to Dark Lord of the Sith, Kun redesigned his lightsaber based on instructions hidden within an antiquated Sith holocron. The finished product was a double-bladed weapon imbued with dark side energy, from which sapphire blades materialized up to 1.5 meters from either end of the hilt.