Possible Gromril Hammer, engraved with runes.
The most skilled Dwarf weaponsmiths make axes and hammers from gromril. Gromril weapons are usually inscribed with runes, and have the appropriate characteristics.[1a]
A gromril weapon has the same characteristics as its steel counterpart, except that it can never be broken by normal means. If a gromril weapon is caught in a swordbreaker, for example, it is the swordbreaker that will break.[1a]