This demon dirk was originally invented by a lazy tinker as a self-oiling dagger that couldn't rust. Upon carrying it, he quickly discovered that he had invented a weapon with more possibilities that he imagined: not only was the dagger protected from rusting, it could more readily cut though fibers (event those of a giant spider's web, thus saving the tinker's life on one important occasion). Most importantly, the tinker discovered (when he let dagger and and its oily coating stray too close to campfire) that the weapon's blade would burst into flame. Reminded of weapons he had seen carried by the Burning Legion, the tinker christened the weapon a "demon dirk" and began selling them.
The blade can be easily ignited, with the sparkler is built into its hilt..