This particular Shishkebab is a Finch family heirloom, created by the grandfather of Abraham Finch out of a ceremonial Japanese blade (a wakizashi) salvaged from a museum. He welded a Schoelt propane tank to the handguard, connecting it to a series of nozzles mounted along the surface of the blade, adding a small pilot light and control lever to effectively control the flames. Although decidedly unsafe, the resulting contraption was far more lethal to his foes than to himself and he went on to establish a family. Unfortunately, his great-grandson, Jake Finch, turned out to have little reverence for history or ancestors and stole the Shishkebab in a poorly-thought-out bid to ingratiate himself with the Forged and Slag when they seized Saugus Ironworks.
The Shishkebab is an immensely powerful close combat weapon and an unique one to boot.
↑Abraham Finch: "Hey, you!Oh sorry, thought you might be one of those Forged maniacs, but you don't have the burns.A group of them took over the old ironworks, and they'll shoot ya as soon as look at ya." The Sole Survivor: "Who are the Forged?" Abraham Finch: "Bunch a trumped up raiders. Obsessed with fire and metal.That bastard son of mine, Jake, snuck out in the middle of the night to join them.He grabbed my granddad's old sword. It's the closest thing I've got to an heirloom.I don't guess you'd be crazy enough to try and get it back for me? I've got caps, if that's what you want." (Abraham Finch's dialogue)