Psionic blade

A psionic blade (or psi blade) is a type of energy blade manifested through the use of psionic powers.

Protoss Psi-blades
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. Executor Tassadar was able to channel his psionic powers into blades without the need for forearm units.

Psi-blades are incandescent, and are usually of a blue-white color. Psi-blades can cut through 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. After the severing of his nerve cords, Artanis demonstrated the ability to wield a psi-blade and warp blade in tandem.

The Zhakul Guardians manifested green psi-blades while under the control of Maar.

The Tal'darim possess red psi-blades, referred to as bane blades, which are pure Void energy drawn from Amon's realm. 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.

Terran Psi-blades
Monomolecular blades 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.

Terran Dominion scientists have developed similar devices for use by ghosts and similar soldiers using protoss technology.