A cybernetic weapon used by my main sona, Xela!
His robot arm can transform into various weapons, one of which is the Discharge Blade.

It is a forearm-extended sword with an energized blade, when activated it has a shell of plasma that allows the blade to cut through metal with ease. It can also emit electric arcs for sustained attack or to stun.
The blade is mounted on a circular gimbal at the end of the forearm, which allows it to pivot for more dynamic movement.
When not in use, the sword telescopes and retracts into the forearm, with a spring mechanism that pops the blade out when activated.