Ümkar (5e Equipment)
From D&D Wiki
Weapon (Warhammer), artifact (requires attunement by a dwarf)
Ümkar was the first weapon forged by the Dwarven god Moradin sharing his power of creation. Ümkar has two sides, one that damages and one that creates.
This magical weapon receives a +3 bonus to attack rolls and damage rolls, and on a successful hit it deals an additional 1d8 thunder damage. If the target is a Giant, it deals an extra 2d8 bludgeoning damage.
In addition, once per day you can use your action to touch a nonliving object with Ümkar, repairing all damage. Touching a nonmagical weapon in this way will transmute it into a +1 magic weapon until the next dawn.
Ümkar weighs 100 pounds. Those carrying it that have strength under 20 has this weight tripled. Additionally if a creature not of dwarven lineage attempts to wield this weapon they suffer 1 level of exhaustion + 1 more for every minute wielded.