Of all the Melee weapons in the Fallout universe, the Shishkabab is perhaps by far the coolest. It's basically a refurbished katana outfitted with a small canister containing potent fuel, and multiple jets used to emit the blade with flames from the canister, adding fiery energy damage in addition to the blade's physical ballistic damage. It can be modded to have a few more flame jets to deal more energy damage. There is no need to search for fuel for this weapon, as has infinite supply.
& Blades manufactured by the Hayakura Company, the SWAN and LOTUS tanto and katana (respectively) are of the sharpest blades in the world. With a Mohs hardness rating of 12 these weapons are used by the upper echelon of assassins and stealth operatives.