Cortosis-weave armor functioned as a type of armor that offered protection against lightsabers. The armor incorporated small quantities of cortosis, a highly sought-after ore known for its capacity to generate an energy feedback loop, which could temporarily disable a lightsaber.
Due to the fact that cortosis weave only had a small amount of cortosis interwoven within its structure, the armor was unable to completely disable an opponent's lightsaber. Instead, armor incorporating cortosis weave simply offered resistance to strikes from lightsabers.
Cortosis weave saw usage as early as 4000 BBY, serving both as an underlay for armor and for improving the durability of traditional melee weapons when facing lightsabers. During this period, cortosis ore appeared to be more readily available; however, it later evolved into a scarcer, more valuable material that offered an unexpected advantage against a force-sensitive adversary.
It is documented that the Yinchorri utilized this armor during the Yinchorri Uprising in 33 BBY. A modified version was also employed by the Jensaarai during a conflict on the planet Susevfi in 11 ABY, where Corran Horn and Luke Skywalker engaged them. The Jensaarai adorned their armor with cortosis weave patterns purely for aesthetics, though the armor retained its practical defensive capabilities. The cortosis used in their armor was acquired through smuggling operations originating from the gas planet Bespin. Furthermore, Shadowtrooper armor, worn by force-sensitive soldiers of the Empire Reborn in 13 ABY, incorporated cortosis weave during battles against Kyle Katarn and members of the Jedi academy based on Yavin 4.