Gehenna is the GRA variant of the Shishkebab, a flaming melee weapon which sets the target on fire upon impact. It appears to run on fuel from the gas tank on the player's back, though its use in-game requires no fuel source.
In comparison to the standard Shishkebab, Gehenna has a more pronounced and brighter flame, its valve is blue instead of the standard red, its handle is black, and the motorcycle gas tank is more rusted. In addition, Gehenna inflicts greater damage, has a higher DPS, and uses fewer Action Points in V.A.T.S.
than the Shishkebab.
Even though its blade is wreathed in fire, poisons can still be applied to the Gehenna's blade. The damage over time from the applied poison stacks with the immolation damage. If the Courier has the Pyromaniac perk and poison is applied to Gehenna, it can become one of the most damaging melee weapons in the game.
As it is constantly on fire, Gehenna will set off gas leaks if the player walks through one with the sword drawn. The same applies if a companion has it equipped.
When a limb is severed by Gehenna while on fire, the flames will never go out.
There are twelve tally marks etched into Gehenna's gas tank, indicating the amount of kills from the previous owner. This is similar to the Ratslayer and the base Shishkebab.
The text "VALVCO" is engraved on the valve.
As with all Shishkebabs, it seems to have an infinite supply of gas.
The flame damage does not stack when applied on enemies.
Behind the scenes
Gehenna is a valley located outside ancient Jerusalem, and was a place where various pagans sacrificed humans by throwing them in fire, and later, as Jerusalem and Judaism developed, waste would be burned there. Due to the increasing population, and thus waste, the fire was said to burn continually, and Jesus, and later Dante Alighieri, used this to produce an image of Hell, which is now the most widespread representation: a place where evil people go to burn for eternity.
Gehenna is Aramaic for “Valley of the people of Hinnom," which is the proper name of the valley of blood, whose name later became synonymous with, and often translated as, hell.
Sometimes when you switch between the 3rd person view and the 1st person view, the flames don't appear. Removing and re-equipping the weapon fixes this problem.[verified]
When used by companions, the blade and tank will not appear. Only the oven mitt on the right hand will appear.[verified]