Flashcut was the sword used by Hiccup Horrendous Haddock III's cousin Snotface Snotlout. Flashcut is a Double-Sided Extra-Biting Supa-Sword.
History
First appearing in How to Be a Pirate, Flashcut is mentioned in the book, but never seen. Snotlout thought he may have had an advantage against Hiccup because he got the latest model while Hiccup had Grimbeard the Ghastly's favorite sword Endeavour.