In one hand he held a very unusual, enormous, double-headed axe. The axe was different in that one blade was a bright and shiny copper gold, but the other blade was rusted and blackened, and deeply scarred.
The Axe of Doom was the primary weapon of Norbert the Nutjob along with Norbert's gigantic sword.
Deciding Hiccup's Fate on Hysteria
The Axe of Doom first appears in How to Cheat a Dragon's Curse, where it was used by Norbert the Nutjob in an attempt to decide the fate of Hiccup Horrendous Haddock III. Hiccup managed to catch the axe midair, a feat deemed impossible.
Norbert also fought Hiccup with the Axe of Doom during their confrontation on the mast of the The American Dream 2 during the sinking of said ship where it was being attacked by a Leviathorgan and was going through a thunderstorm, where the axe was struck by lighting. This resulted in the axe being lost, when it fell into the ocean.
The Axe of Doom is a large double-headed axe topped with a skull figure at its tip. One blade was a well-burnished dark golden color. The opposite blade was very unkempt - rusted, blackened, and pocked. Despite the uneven care, both blades were sharp.
Norbert used the Axe of Doom to fight, as well as decide the fate of his enemies. Norbert would spin the axe high into the air, and if it landed on the gold part, the victim would live. And if it landed on the black part, the victim would die.