How to Steal a Dragon's Sword is the ninth installment of the How to Train Your Dragon series, by Cressida Cowell. It was released in 2011.
Hiccup, Fishlegs, Camicazi and all other Warriors-to-be from all the other tribes are to go to Flashburn's School of Swordfighting the hard way, which is by climbing a sheer cliff face. While the adults use the easy way, the first wave of the Dragon Rebellion attacks Hiccup and the others. When they reach the school, they find it deserted. The adults arrive, bearing signs of another attack. The chiefs find the witch Excellinor in a cauldron, where she lies, telling them Flashburn and the others died fighting off Rogue Dragons. She tells them the only way to defeat the dragons is by electing a new King of the Wilderwest. The new king will have the King's Things and will be decided by the Swordfighting tournament on the New Year. Hiccup already has Endeavour, the Ticking-thing, the Roman Shield, the American Arrow, Toothless, the ruby heart, the throne of the Wilderwest, the Key-That-Opens-All-Locks and only lacks the Crown and the Dragon Jewel. Excellinor also tells the Vikings Hiccup set Furious free and caused the War. The Outcasts also appear, with Alvin in charge again. They are also in the Competition because of the line of Thugheart. Soon, all the very good swordfighters get mysterious injuries after visiting Excellinor to tell their fortunes.
Stoick goes missing as well and Hiccup goes to the Witch's Hut to find him. There, Excellinor tells him he must find the crown in 3 hours or his father dies. Hiccup, Camicazi, Fishlegs and their dragons enter the maze and find Flashburn. Flashburn tells them Excellinor tricked him into finding the crown 20 years ago, and he still hasn't succeeded. Using the ticking-thing, Hiccup finds the crown, which Wodensfang guards, the dragon of Hiccup Horrendous Haddock I. After hearing Hiccup out, Wodensfang allows Hiccup to take the crown and live, but they are soon surrounded by Red-Rage dragons. Hiccup gets them out using a clever tactic by telling them Brain Pickers attack them, the most feared dragon in the Archipelago. When Hiccup gets out, Excellinor stabs him with her fingernails stained with Vorpent Venom, but Hiccup tells her he's immune to it, as he ate a POTATO. Hiccup frees his dad (and UG), and competes in the competition. Stoick and Hiccup meet in the final, but after telling Hiccup he will not set the dragons free, Stoick loses to Hiccup, as Hiccup's determination to stop the war allows him to win. Unfortunately, Excellinor noticed Hiccup's Slavemark and asks Snotlout to hit his helmet off. Hiccup is banished and Stoick is banished as well, for keeping Hiccup even though he is a runt. Fishlegs, however, refuses to turn his back on Hiccup and gives him his lucky lobster claw necklace. As Alvin is crowned the New King of the Wilderwest, Furious attacks, and all the domestic dragons turn against the Vikings (because Alvin's first decree was to enslave them even more) and chaos breaks out. Hiccup distracts the dragons and escapes with Wodensfang, the Windwalker and Toothless. In the end, Hiccup finds the map to the Dragon Jewel in the Will and Testament of Grimbeard the Ghastly hidden in Endeavor's secret compartment. Hiccup vows to find it and put an end to the war.