Darth Mekhis created an army of Sith Knights from imprisoned Jedi who had been corrupted by her power and altered by her science. During the Cold War, Darth Mekhis gave a number of Jedi who were captured by the reconstituted Sith Empire's forces during the Great Galactic War the choice of joining the Sith willingly. When they refused, she turned them into her Sith Knights, cybernetic Sithspawn slaves who were no longer the Jedi that they used to be.
These humanoid creations were cybernetically outfitted with plates around their bodies along with two large red eyes. An army of such beings were created by the Dark Lord of the Sith, Darth Mekhis who used captured Jedi that had been altered by her science and corrupted by her power. Those Jedi that refused to join the Sith cause were transformed into the feared Sith Knights that acted as agents for their master. The process of transformation meant that these Jedi were no longer the beings that they used to be.
Initially, there were no known vulnerabilities present within the Sith Knights. In terms of equipment, these warriors were outfitted with electrostaff-like weapons along with stealth field generators that made them invisible to the naked eye. They were also outfitted with sensors though irradiated environments were capable of scrambling these systems.
In the Great Galactic War, the Sith Empire emerged from centuries of hiding in order to bring ruin to the Galactic Republic and the Jedi Order that had nearly destroyed them so long ago. During this time, the Dark Councilor Darth Mekhis managed to capture a number of Jedi. These prisoners had a simple choice; either dedicate themselves to the dark side of the Force or be grafted into her machines. Those that refused to join were thus converted into Sith Knights with no trace of their former selves remaining. The end of the conflict saw the signing of the Treaty of Coruscant where seven seemingly unimportant worlds were given over to the Empire in exchange for peace which became marked as the Black Sectors. Among these included the Vesla system that was gifted to Darth Mekhis where she conducted her dark experiments. Following the war, Jedi Master Ngani Zho managed to live in the Vesla system for ten years where he battled against her dark schemes and witnessed countless horrific acts such as the Sith Knights that scarred his memory making him only remember fragments of his time on that world.
After Zho departed the Vesla system in the Cold War era, Darth Mekhis sent her agents in order to track down the Jedi Master in order to eliminate him. This led to the Sith Lord dispatching a trio of her Sith Knights from the Javelin Dreadnought with the intention of her creations hurting him the same way his apprentice Satele Shan had harmed Mekhis during the war. The cybernetic creations were dispatched and traced their quarry to the planet Taris. Whilst telling stories to a crowd, the elderly Jedi Master was met with Theron Shan, an agent for the Republic Strategic Information Service who was tasked with retrieving Zho. As the two departed the immediate area, the Jedi Master and Shan detected the presence of cloaked beings following them which led to the RSIS agent deploying a grenade that generated an energy pulse that broke the Sith Knight's stealth screens. As the Sith Knights chased the pair into the tunnels of Taris, Theron and Zho attempted to reach Theron's ship and narrowly evaded the clutches of a Sith Knight by the intervention of Teff'ith who used a blaster to force the cyborgs back. One Knight managed to land onto the ramp of the starship and the lightsaber of Nghani Zho was used to throw it off leading to the cyborgs failing in their initial assignment.
A number of Sith Knights accompanied Darth Mekhis onboard the Sun Razer in the Vesla system where they served as part of her personal guard. They were deployed to fight Theron Shan after he escaped custody and intended to lower the shields protecting the Sun Razer from the star it encompassed. The Knights managed to apprehend Shan but he used a stun dart to knock out Darth Mekhis and the Sith Knights were accidentally shot by a Imperial soldier. The defeated Sith Knights allowed Theron Shan to complete his objective and destroy the Sun Razer whereupon he escaped from Imperial space.