From LSWiki

Flux weapons are weapons which use psionic energy as a contact medium. They use the skill psycholeptesis(?) as part of their effective control. Flux weapons can have flux capacitors attached, which presumably increase their effectiveness. Unfortunately I do not know many details, so hopefully someone can fill in more blanks with factual data.

Flux Sword

    This steel rod, energy-focusing patterns etched into its surface, is the
handle of a flux sword, a psionic weapon.  When grasped and its command word
is subvocalized, a blade of coherent psionic energy will spring forth from it.
Creating and maintaining this energy field is psychically draining to a
degree, and while anyone can bring it into being, the weapon only achieves
full effectiveness in the hands of one with the psionic skills to properly
control the field.  The flux sword is returned to its inactive state by
subvocalization of another command word or when the wielder lets go of the
handle.  It is in perfect condition.  It looks about three fifths of a dimin
across and twelve and a half dimins long.  It weighs about thirty dekans.

Flux Sword Activation Words

Activation: xanla Deactivation: limir