Strange alloy from the Iron Kingdom. Resembles steel that has shadows flitting across its surface, it is extremely hard and flexible.
In the Iron Kingdom it is very common, more so then common steel, and related minerals. However outside of the Iron Kingdom, it is extremely rare as the sale to those outside is banned. It can only be had if given as a gift.
The Fallen Emperor was known to possess a great horde of items made of shadowsteel, received after conquering the Iron Kingdom.