Valyrian Steel

Valyrian Steel is a rare form of steel, known only to be forged in the old Valyrian Freehold. The production of Valyrian steel is said to have involved magic, giving it special qualities and nearly unattainable since the Doom of Valyria. Valyrian Steel is known to be far lighter than normal steel, far stronger, and able to hold an edge far longer. It is distinctively rippled in appearance.

These swords are immensely valuable and closely-held by those who possess them, oftentimes family heirlooms with lengthy and well-documented histories. A number of these swords have made it across the Narrow Sea to Westeros.

Known Valyrian Steel Swords
Multiple houses across Westeros possess Valyrian steel swords. Many have been lost to time, but those known to exist today are listed below.

The Kingdom of Winter

 * Ice - a Valyrian steel greatsword of House Stark, its blade a dark grey and as wide across as a man's hand from fingertip to heel.
 * Longclaw - a Valyrian steel bastard sword of House Mormont, the steel pale and the pommel a snarling bear's head carved from stone.

The Kingdom of Mountain and Vale

 * Lady Forlorn - a Valyrian steel sword, wielded traditionally by the lords of House Corbray. Its pommel is inset with a heart-shaped ruby, and the steel itself is smoky grey.
 * Lamentation - a Valyrian steel sword, wielded by knights of House Royce.

The Kingdom of the Isles and Rivers

 * Nightfall - a Valyrian steel longsword, wielded by the men of House Harlaw. The steel is an inky black, and the hilt decorated with iron fittings.
 * Red Rain - a Valyrian steel sword, wielded by the men of House Drumm. The steel is reddish in hue.

The Kingdom of the Rock

 * Brightroar - a Valyrian steel greatsword belonging to House Lannister of Casterly Rock.

The Blackwater Confederation

 * Servitude - a Valyrian steel helmet, which is worn by Lord Protector of Blackwater. It's not hereditary, it changes its owner once new Lord Protector is elected.

The Narrow Sea Houses

 * Blackfyre - a Valyrian steel bastard sword belonging to House Targaryen. The crossguard is decorated by dragons' heads, and the pommel is a ruby.
 * Crab's Claw - a Valyrian steel axe wielded by the men of House Celtigar.
 * Dark Sister - a Valyrian steel longsword belonging to House Targaryen. The blade and the sword are slender, said to be forged for a woman's hand. The crossguard and pommel are styled to look like flames and forged from gold, and there is a ruby set in the center of the crossguard.
 * Dragon's Tooth - a Valyrian steel dagger belonging to House Targaryen. It has a hilt of dragonbone, but unremarkable coloring of its steel.

The Kingdom of the Reach

 * Heartsbane - a Valyrian steel greatsword wielded by the Lords of House Tarly.
 * Orphan-Maker - a Valyrian steel longsword belonging to House Roxton.
 * Vigilance - a Valyrian steel longsword belonging to House Hightower.

The Principality of Dorne

 * Dawn - a greatsword forged out of a fallen meteor with a blade as pale as milkglass. While not made of Valyrian Steel, it possesses many of the properties of the metal and is often grouped in with such weapons.  Wielded only by knights of House Dayne deemed worthy enough to carry it and possess the title "The Sword of the Morning".