A cortosis blade used against Darth Vader
Cortosis swords, which were also known as cortosis blades, were bladed melee weapons either crafted entirely from cortosis or enhanced with it. These blades were produced by various manufacturers and saw widespread use around 3956 BBY during the time of the Jedi Civil War, and they were created for a variety of purposes.
One primary reason for their creation was cortosis's unique ability to impart lightsaber resistance to other materials when combined with them; this led to its incorporation into numerous vibroswords during the Jedi Civil War. Another application involved the creation of blades made purely from cortosis, designed to briefly disable lightsabers, granting the wielder a tactical edge. These pure cortosis blades were often capable of deactivating a lightsaber for minutes at a time, proving their effectiveness in combat.
During the Invasion of Naboo in 32 BBY, the Trade Federation deployed a type of assassin droid that was armed with cortosis swords to fight Jedi. Obi-Wan Kenobi along with Qui-Gon Jinn were able to destroy many of these droids.
Prior to and during the Clone Wars, Harll, a Farghul male, brandished a cortosis blade that he had received from the Morgukai warriors. During the Conclave on Kessel, Jedi Master Shadday Potkin engaged Darth Vader using a cortosis blade. Vader ultimately killed Potkin, subsequently using the same blade against Jastus Farr on Kessel.