Item from House of the Dragon by George R.R. Martin
Magical steel forged in the Freehold of Valyria using dragonfire and blood magic. Lighter, sharper, and near-indestructible. The secret of its making died with Valyria.
Valyrian steel is a legendary metal forged using techniques lost in the Doom of Valyria — techniques that involved dragonfire and, according to some sources, blood sacrifice. Blades of Valyrian steel are lighter than castle-forged steel, hold an edge indefinitely, and display a distinctive rippled pattern in the metal. They cannot be newly forged, only reforged from existing Valyrian steel by a handful of smiths who know the art. Every Valyrian steel blade in Westeros is an heirloom — a piece of a lost civilization carried forward by houses that may not understand what they possess. Blackfyre and Dark Sister are among the most famous examples, but dozens of houses hold their own Valyrian blades.
Magical steel forged in the Freehold of Valyria using dragonfire and spells. Lighter, stronger, sharper than castle-forged steel. The secret of its making died with Valyria. Only reforged, never newly created.
Also known as: Valyrian steel, dragonsteel