Material
The Dradrien's superfine production steel — impossibly light hauberks, razor-edged blades, and the Sky Riders' enchanted spurs all come out of the Yltedene forges.
Yltedene steel is the production-grade alloy Master Suhi and his Dradrien produce at the foundries of Yltedene in the Magelaw. It is the metallurgical revolution of the series: Suhi produces it by blowing impurities out of molten iron with air at scale, a process he dismisses as mere metallurgy rather than magic. The result is a fine, light, enormously strong steel the human smiths of the Kingdom cannot match, and the Magelaw's strategic advantage on the battlefield.
Yltedene steel is used for everything from hauberks (Terleman's knights are equipped head-to-toe) to Master Cormoran's own mageblades to the razor-sharp spurs fitted to Dara's and Nattia's giant hawks. Cormoran names it explicitly as the equaliser against the Enshadowed in Arcanist:
Learn the term, 'Yltedene Steel.' For it shall be the swords forged in Yltedene that you will impale yourselves upon!Master Cormoran, Arcanist