This section contains information from the Warcraft RPG which is considered non-canon.
Mithril is a rare, silvery, glistening metal that is lighter than iron but just as hard. When worked like steel, it becomes a wonderful material from which to create armor; it is occasionally used for other items as well. Most mithril armors are lighter than other metals. An item made from mithril weighs half as much as the same item made from other metals. In the case of weapons, this lighter weight does not change the weapon’s ease with which it can be wielded (whether it is light, one-handed or two-handed). Items not made primarily of metal are not meaningfully affected by being partially made of mithril.[1]