An unusual form of lightsaber crystal, etaan formed in the depths of caverns deep within the crust of Etai, appearing no higher than five hundred meters below the surface, and most often deeper than a thousand meters, making them incredibly difficult to find. Etaan possessed a unique property, in that they echoed sound with a humming resonance, a quality that assisted searchers. Once harvested, their resonant properties remained, and when incorporated into a lightsaber hilt, the blade emitted thrummed in harmony with the motion of the blade. Responding well when clashing against another blade, the weapon gave off a near-deafening crack and flared with energy. While a lightsaber powered by an etaan would cause others to bounce off its blade, blaster bolts absorbed some of the energy from the resonant blade and were increasingly dangerous if redirected at a target.
- Endless Vigil (First mentioned)