How to steal a dragon's sword

Viking Berk heir Hiccup Horrendous Haddock III and his dragon, Toothless are target of dragon rebellion -- filled with the meanest Razor-wings, Tonguetwisters, and Vampire Ghouldeaths. Only a King can save them, a champion with all of the King's Lost Things. Hiccup will have to outwit a witch, fight his arch-enemy, and beat back an army of bloodthirsty dragons with just one sword.