Inferno

The Dragon Blade, also known as Inferno, is a retractable sword that serves as Hiccup Horrendous Haddock III's main weapon. The sword has several features, most notably the ability to become enflamed.

History
As Hiccup began exploring further away from Berk, he began to discover more species of dragons and so created the Dragon Blade, also known as Inferno. It was created for the purpose of pacifying any wild dragon that he and Toothless came across. It also helps escape and remove the amber from a Death Song. Hiccup got the idea of the Dragon Blade for the first time when he noticed the qualities of the saliva of a baby Monstrous Nightmare, during Berk's first Snoggletog with the dragons. It is in Tone Death when the Dragon Blade was forged, but it is shown in the 4th season of Race to the Edge and the second film that Hiccup uses it to train and pacify the wild dragons he comes across them on his travels.

Dragons: Race to the Edge, Season 3
In Tone Death, Hiccup first used a knife by coating its blade with a bit of Hookfang's gel and had Belch ignite the tiny weapon with his spark to cut Tuffnut's Chicken free after she was encased in Garffiljorg's death song amber. Hiccup began to tinker more with it, using a larger blade and a built in lighter. This came in handy when the gang became trapped in the adult Death Song's blast. Astrid commented that if the blade was twice as big it would be a really cool sword. Hiccup dubbed his creation "Inferno," but the other Riders were unsure of the name. Hiccup said he would come up with a different one, as well as lengthening the shaft, adding another canister for Nightmare gel, and make the gas canister airtight. Getting excited, Hiccup takes off, leaving Astrid saying that's the last they'll see of him that week. It was later shown that Toothless had to blow out the flame to deactivate the fire, as seen in Family on the Edge, when Dagur shows up at Hiccup's hut and is seen inspecting the blade with the fire on.

Dragons: Race to the Edge, Season 4
In Midnight Scrum, Hiccup used Inferno to cause a sheep stampede to scare off Ryker Grimborn and a pair of Dragon Hunters. He tried to use it against Krogan, but was disarmed quickly. He also tried to calm down the Small Shadow with it but failed. Hiccup then used Inferno to defend himself, Fishlegs, and Mala from the Fire Terrors of Caldera Cay's volcano in Out of the Frying Pan, only to discover that the dragons eat fire. He also was seen trying to use it to possibly pacify the Triple Stryke, Sleuther, in the episode Blindsided, but its flame was extinguished by the rain.

Dragons: Race to the Edge, Season 5
Hiccup had improved upon Inferno since season 4, as he said he would in season 3, extended the blade. It's hilt looked more like it did in How to Train your dragon 2. He used it more for combat as he fought berserkers in Something Rotten on Berserker Island and was seen training with Astrid in Dawn of Destruction.

How to Train Your Dragon 2
Hiccup first used the Dragon Blade when Stormfly had been captured in a net, fired by Eret, Son of Eret and his crew, to intimidate the Dragon Trappers and cut Stormfly free from the ropes of the net.

He later used it in front of the trappers again to draw their attention to the fact that he was still armed by igniting the blade and, after surrendering it to the trappers, tricked one of them into releasing the Zippleback gas and igniting it. Eret tried to get rid of it twice by throwing it off of the ship, but Stormfly, thinking that he was playing 'fetch' flew after it and brought it back to his feet both the times.

After being captured by the Dragon Thief, who was unknown to him at the time, was his own mother, and her dragons. He initially tried to use the Nightmare saliva to pacify them but was unsuccessful, due to the sheer amount of dragons surrounding him. Following this, he primed Inferno with one of the Zippleback gas canisters that he kept on his boot and sprayed it around him in the form of a circular fire-line before igniting it, succeeding in calming them before his mother interfered.

When he fought Drago Bludvist on Berk, he used the Zippleback gas as he flew past his enemy to throw him off the new alpha Bewilderbeast and, after making it safely to the ground, threw Inferno while the blade was still lit to prevent Drago from reaching his bullhook, the tool he used to control his Bewilderbeast.

Abilities

 * Monstrous Nightmare Saliva: By placing a small canister of Monstrous Nightmare saliva inside the hilt, Hiccup was able to coat the blade with the substance so that when ignited it produced replicated dragon fire, which convinced most - if not all - wild dragons that Hiccup was one of them. This ability could also be used to fight and intimidate humans.


 * Hideous Zippleback Gas: By placing a small canister of Hideous Zippleback gas inside the hilt, Hiccup was able to release the gas through the pommel and ignite it to create an explosion, in the event that Hiccup became surrounded by dragons, to prove to large groups of dragons simultaneously that he was 'one of their own'. This ability could also be used to fight or intimidate humans. The gas, using the sword, could also work like a blowtorch or a flamethrower.


 * Lighters: Inferno possessed two lighters to create sparks; each at opposite ends of the hilt as one was used to ignite the Nightmare saliva while the other was used to ignite the Hideous Zippleback gas.


 * Retractable Blade: The blade of Inferno was hollow to allow pieces of the blade to slide into each other before eventually sliding into the hilt, where it is soaked with Monstrous Nightmare Saliva.

Appearances

 * Dragons: Race to the Edge, Season 3
 * Dragons: Race to the Edge, Season 4
 * Dragons: Race to the Edge, Season 5
 * How to Train Your Dragon 2
 * Dragons: Rise of Berk
 * School of Dragons

Trivia

 * According to The Art of How to Train Your Dragon 2, and Race to the Edge episode, Tone Death, the sword is nicknamed Inferno.
 * The Dragon Blade is one of three tools used to influence or control dragons, along with Valka's staff and Drago's bullhook.
 * Given the blade's features, most notably its ability to retract into the hilt, Inferno may be a reference to the lightsaber, the signature weapon of the Jedi and the Sith from the Star Wars franchise.
 * A deleted scene shows that it is possible to use the saliva of dragons other than the Monstrous Nightmare for the blade, like the Stormcutter.
 * Though in that scene, it is shown that the Stormcutter's saliva produces an uncontrollable flame on the blade.
 * The Dragon Blade appeared in the game Dragons: Rise of Berk as a collectable in completing collections.
 * The Hideous Zippleback gas function is said to be inspired by the Original Dragon Eye, which emits stun gas as a security mechanism.
 * Unlike most dragons, the Small Shadows don't like the blade.
 * Inferno is also called The Dragon Blade.