Mjollnir/Lore

Mjollnir is a powerful divine weapon in the lore of Dota 2.

Description
This magical hammer is the signature weapon of Thor, forged for him by the dwarves Brok and Eitri. It has the power to harness lightning and can only be wielded by its owner.

Heroes
is impressed by the power of Mjollnir, but still believes that it is no match for her Brightmaul.

implies that this hammer can only be wielded by its owner, like the original. And yet she can lift it, which confuses her.

recognizes this weapon, merely calling it a "divine plaything" in spite of its godly power.

World
states that this weapon is known in Claszureme whose inhabitants speak of it in hushed tones.

Others
What is presumably copies of Mjollnir are sold by Keepers like the Secret Shop's owner for gold. These copies don't inherit the restriction of the original, allowing others to hold it.

Trivia

 * The VFX of Mjollnir's Static Charge is an arc of lightning in the shape of a triquetra, a symbol that is sometimes seen in some of Mjollnir's real-life depictions.