The volkite charger is a relic of a lost golden age, a thermal ray-weapon from the height of humanity's technological glory. It fires a beam of deathrays that heats its victim's body until it flashes to ash from within, and a struck foe will often burst into flame and cook those pressed close around him, so that a single shot can undo a whole knot of warriors.
Volkite weapons were once wielded by the millions during the Great Crusade, when the forges of humanity could still build wonders. Those arts have all but died in the long centuries of decline, and each surviving charger is an irreplaceable treasure, coaxed back to life by tech-priests who tend but no longer truly understand the machine in their hands.
Today they are borne by those few forces rich enough in ancient wargear to field them — chiefly the Adeptus Custodes, the war-covens of the Adeptus Mechanicus, and the household troops of Terra's oldest institutions. To see a volkite fire, its beam a searing bar of light and its victims sloughing into ash, is to glimpse the terrible splendour of an age the Imperium can no longer reach — and a measure of how far it has fallen since. Every discharge spends a little more of an irreplaceable inheritance, and the adepts who tend these weapons do so in the bitter knowledge that when the last of them finally dies, the secret of their fire may be lost to humankind forever.