The Sith Trooper is a very agile and mobile unit. Already being faster than most units the "combat rush" ability allows it to move almost as fast as the Droideka unit, while also being able to regenerate a portion of their health with each kill.
Its weapon is similar to the TL-50 in the way that both weapons also have an alternate fire. Compared to the TL-50, the Quarrel Blast deals more damage, has far better range (being very good at range for an alternative fire) and travels in a straight line. The Quarrel Blast can also lock onto enemies if far away enough, similar to Leia's Alternate Fire. It can almost one-shot three of the four default trooper classes and can be used to finish off a weakened unit if they are weak enough. Heroes will take significant damge, but it will just be a fraction of their health. However, if used repeatedly, the damage can become greater than their health regeneration can later undo.
With the Oppression Grenade, you can be sure to hold off heroes a lot better! A powerful weapon that is able to restrict health regeneration of an enemy, depending on your situation, this can be deadlier to enemy heroes and special units, who have more health than regular infantry. Heroes need to regenerate to survive.
With the Combat Rush ability, you are able to traverse the battlefront at a speedy rate, while regening your health faster than normal. Watch out, runaways!
The Sith Trooper's Seeker Tactics ability reveals enemy units in the area of the trooper, the number of units expanding for every kill, allowing for a recon of enemy movements and positions and the ability to ambush.
Although Sith troopers were canonically affiliated with the First Order, Sith troopers were actually soldiers raised by a secret cult of Sith loyalists and followers of Emperor Palpatine, the Sith Eternal, and were the soldiers of the Final Order.
Very few Stromtroopers, Imperial or First Order, have ever been to a world of the Jedi or Sith, and Sith troopers are among them.