Sith troopers, also known as the Sith soldier or Abeonis' fists, were the foot soldiers of the Sith Order of Decreto during the Sith Crusade. Their distinctively faceless armor and the sadistic nature of those who wore it set the Sith troopers apart from the rivals.
The first Sith troopers of Abeonis' armada were a crack force of Galactic Alliance soldiers who had been assigned to The Soiyo before its mission into the Unknown Regions, they were later joined by the loosely organized military of the weakened Sith Order of Decreto during the years of its conquest by Darth Abeonis; and eventually by idealistic Sith collaborators from conquered worlds. The weak were siphoned out through the merciless Sith training schemes, resulting in an efficient and powerful fighting force. The fear present in each trooper not only spurred them on in battle, but also prevented them from betraying their Sith Masters.
During the first few years of the Sith Crusade the standard Sith trooper was more than enough of a challenge for their counterparts (the Colonial Phalanx, the Rakata and Stormtroopers), but with the invasion of the Galactic Federation of Free Alliances in 61 ABY many new forms of Sith troopers came into creation, including the highly sophisticated and greatly feared SpecOps.
The Sith troopers continued to served the Sith Order of Decreto throughout the conflict, often taking inspiration for the armor of their enemies, including the Stormtroopers of the Imperial Remnant.
The standard armor of the first Sith troopers was a reflective silver with a black face mask hiding the soldier's face, and was designed to inspire fear in the enemy, as well as provide all the necessities of modern warfare.
As the Sith Crusade progressed, many different versions of the armor developed, including that of the Sith Snowtrooper and the SpecOps. But throughout the fluctuations in look and design, the armors always maintained the distinctive face mask, which continued to inspire fear in the hearts of their enemies.
The most radical departure from the norm in terms of design was in the form of the SpecOps, whose armor emphasized mobility above protection, as it was the SpecOps job to avoid being hit in the first place. The armor also contained several functionalities not included in those of the standard Sith trooper.
Keeping more closely to the norm however, following the Sith conquest of the Imperial Remnant in 58 ABY, aspects of the Stormtrooper armor design were incorporated into the armor of the Sith trooper, including new functionalities and abilities, including lightweight padding, moving plates and additional protection.