Nobody knows what item are the ancient steel but the NPC Edowir knows how to describe all of them :
Mesh Kaha Rogh
Edowir: The so-called singing steel causes a constant humming while it is forged. It is said this was a sign of its absorbing magic powers in the process, and it was presumably easy to enchant. Sadly, the secret where to mine or how to create this ore has been lost in the course of time.
Za'Kalortith
Edowir: This is the metal of 'evil', the hell-forged iron no ordinary flames can melt. It is rumoured to be harvested in hell from iron rocks in which damned souls were imprisoned.
Uth'Byth
Edowir: This steel absorbs magic. While it is of inferior quality compared to ordinary steel, its absorbing qualities make it important though.
Uth'Morc
Edowir: What makes this black steel exceptional is its lightness and peculiar property of lacking the common steel 'noise'. It is also called 'silent steel' or 'thief's steel' for this reason.
Uth'Amon
Edowir: The luminescent brightsteel is used for artwork mainly. In ancient times, items of great magic power were crafted using brightsteel. Those crafts were lost with the races who held the secret to them.
Uth'Maer
Edowir: The dwarfs call it heartiron and claim it is part of the heart of The Big Old One. Therefore, they hold it sacred and its use is limited and regulated.
Uth'Doon
Edowir: The dwarven high steel is relatively common but expensive and still hard to come by. The elite dwarven weaponry and armours are made of Uth'Doon.
Zatragil
Edowir: The so-called dreamsilver is a legendary metal. Almost everything we know about it are rumours only.