Vibrostaff

Vibrostaves were melee weapons that came in single and double-bladed varieties. These staffs had a rounded hilt roughly three feet long, that contained a vibromotor, a mechanism that caused the blades to vibrate at an incredible speed, causing even the slightest glancing blow to become a gaping wound. 
The hilt also contained one or two blades roughly 2 ½ feet long, sharpened to a razor's edge that could be activated individually or simultaneously. The blades' cortosis weave allowed them to parry the blows of lightsabers, energy swords, or blaster bolts. 
Double-bladed vibrostaves were the predominant weapon of choice for Royal Guard trainees. Taking an idea from his deceased apprentice, Darth Maul, Emperor Palpatine had double-bladed vibrostaves crafted to equip his newly formed corps of Imperial Guards. Palpatine employed one of the greatest melee weapons designers in the galaxy, Kolvo Weapons Manufacturing, KWM as it was more commonly referred to, to produce a limited number of these weapons. 
Once the order was completed, the manufacturing facilities were the subject of an assault by TIE Bombers, effectively destroying all blueprints and machinery capable of producing these unique weapons. 
A Royal Guardsman trained in the martial art of Echani could wield these durable, lightweight weapons almost like a third limb in combat.