The Valyrians were familiar with dragon glass long before they came to Westeros. They called it ---- which translates to "Frozen Fire" in Valyrian and castle texts tell of how their dragons would thaw the Stone with dragonflame until it became molten and malleable. The Valyrians then used it to build their strange monuments and buildings without seams and joints of our modern castles.

When Aegon the Conqueror forged his Seven Kingdoms, he and his descendants would often decorate their blades with dragonglass, feeling a kinship with the Stone. The royal fashion for dragonglass ornamentation soon spread throughout the Seven Kingdoms to those wealthy enough to afford it. Hilt and pommels were and are the most common for dragonglass is to brittle to make a useful crossguard. Indeed its very brittleness is what regulates it to the great houses and most successful merchants