Jarnbjorn (Earth-616)

History
Jarnbjorn was a Dwarven-forged Battle Axe wielded by Thor long before he wielded Mjolnir.

In the 9th century, after attempting numerously to wield Mjolnir, Thor used Jarnbjorn as his common choice of weapon. He fought many foes with Jarnbjorn, foes like Frost Giants, Trolls and Dragons.

In the 11th Century, Thor faced off against a celestial-powered Apocalypse. Seeking revenge after losing, Thor blessed Jarnbjorn with his blood, granting it capable to pierce Celestial armour. Though Thor eventually lost Jarnbjorn, which was found by Kang the Conqueror at Baron Mordo's tomb in Brazil.

The axe was later stolen by the Apocalypse Twins from Kang. Uriel and Eimin used the axe to kill the Celestial Gardener outside the Starcore Space Station, and became the new Apocalypse. The murder was apart of a plan by the twins to frame Earth for the Celestial Gardener's death and for the Celestial Exitar to destroy it. The twins managed to convince Scarlet Witch to perform a spell to transport every mutant to their ark before Earth's destruction, leaving humanity to die with it.

In a divergent universe (Earth-13133), their plan would've succeeded, but in this said universe (Earth-616), the remaining members of the Avengers Unity Division arrived and threw a wrench in the twins' plan. Thor retained Jarnbjorn and used it once more to kill Exitar by craving down on its neck.

Jarnbjorn was placed into the Asgardian Armory. When Thor became unworthy after the battle with Nick Fury on the Moon, Thor wielded Jarnbjorn once more. While fighting Malekith and an army of Frost Giants under the ocean, Malekith used Jarnbjorn to cut off Thor's left arm.

Attributes
Forged by Dwarves, Jarnbjorn is sharper than any Earth weapon and can cut through anything. Jarnbjorn has an enchantment placed over it to make it indestructible, and can be used to defend any attack, even Apocalypse's optic beams. In addition, Thor placed his own enchantment that makes it powerful enough to destroy Celestial armour or Celestial technology.