White Steel

White Steel is the eighth tier of quality for medium, heavy, and massive armor, as well as swords, maces, daggers, axes, greatswords, mauls, battleaxes, staves and metal shields. It is only available in the Awakening expansion.

Not much is given on the metal itself, but judging by it's higher ranking over dragonbone, it is probably extremely strong steel. It is likely very rare, as well.

Of note is that Asala, Sten's greatsword, was said to be made of White Steel. However, in the original version of Origins, there is no White Steel tier, so Asala is instead Steel, the far inferior third tier.