Through a protoss generating psionic energy, psi-blade focusers mounted on forearm units contain and channel this energy, said units being located on power and light armor suits, used by zealots and high templar respectively.ExecutorTassadar was able to channel his psionic powers into blades without the need for forearm units, as well as extend the length of his psionic blade become whip-like and hit distant targets. Psionic blades would cauterize as they cut, making combat among protoss generally bloodless.
Psi-blades are incandescent, and are usually of a blue-white color. Psi-blades can cut through almost any material regardless of density, though can be parried by other psi-blades and warp blades. Over time, the Khalai have further refined psi-blade focuser construction, allowing psi-blades to increase in power as a zealot's fury mounts in the heat of battle.
The Dark Templar have further refined psi blades into much more powerful warp blades through infusing them with both Void energy and their burgeoning psionic power. After the severing of his nerve cords, Artanis demonstrated the ability to wield a psi-blade and warp blade in tandem.
After the fall of Aiur, some Khalai protoss adopted the way of the Nerazim and returned to the planet to wage a secret war against the zerg. These avengers wielded psionic scythes, modified versions of psionic blades.
The Tal'darim possess red psi-blades, referred to as bane blades, which are pure Void energy drawn from Amon's realm, as apposed to pure psionic energy like Khalai protoss's psionic blades or a mixture of both Void and psionics like the Dark Templar's Warp blades. Ancient Tal'darim legends speak of masters who could use them to tear planets in half. Khalai protoss possessed by Amon, including Artanis and Selendis, were able to manifest red psi-blades, as could Emil Narud. The Tal'darim under Narud's command at Skygeirr Station wielded psi-blades of a blue-white color though, as did the Tal'darim under Executor Nyon.
The monomolecular blade utilizes its wielder's psionic energy to hone an edge that has been sharpened to a microscopic degree, allowing it to cut through both physical armor and energy shields.
This article or section contains information about StarCraft: Ghost, which has been declared non-canon. Elements may be taken as 'flavor lore' however. The content may be significantly out of date. Please do not add speculation to this article, and remember to cite a published source for details.
In StarCraft II, psi-blades are colored in accordance with player color in multiplayer games. Some fans reacted negatively, but a compromise was never reached.
Exceptions within the campaigns of StarCraft II are the yellow psi-blades of Karass's zealots, and the green psi-blades of the Zhakul Guardians. In the case of the Guardians their team color (black, not available in multiplayer) is separate from their psi-blade color.
The ghost model has an unused animation for using a psi blade.