The Stretchapoint is a type of sword with "extra sharp sides". It is very long and straight. Its design is meant to act as an extension of the swordsman's arm, especially if he or she has short arms.
Got a lot of LENGTH to it, my boy, It'll make up for your shortness of arm. Give you a better reach.
— Stoick to Hiccup in Book 2
Stoick the Vast gave a Stretchapoint to Hiccup to replace the Swiftpoint Scaremaker he lost at sea. It is claimed to be of use to short-armed people because of its length. Due to its length, Hiccup has an especially hard time using it, being very difficult to keep it steady and also shifting his center of gravity such that Hiccup would tip over. The Stretchapoint also inhibits his ability to escape the Skullions on the Isle of the Skullions, often tripping him up. Hiccup lost this sword also, left on the Isle of the Skullions.