The Swords of Ilkan are two legendary twin blades that have the power to open portals to other dimensions and non-canon artifacts within the Mortal Kombat universe. They appear in the 10th episode of the animated series Mortal Kombat: Defenders of the Realm, called "Swords of Ilkan".
Together, the combined two swords have the ability to open portals to another realms. The Swords of Ilkan were originally created in the Crystal Realm, whose once grand civilization fell victim to Shao Kahn's aggression, and one of them was housed in a temple within that realm while the other one was taken away.
Kitana and Sonya found the blade, but instead of giving it to Zara, Kitana wanted to fight. Zara was defeated and thrown into the void, and Kitana threw the swords into a portal. They were never seen again afterwards.