According to Reddit user jumpman72, the text accompanying the drawing read as follows:
The Valyrians were familiar with dragonglass long before they came to Westeros. They called it [some Valyrian words] which translates to 'frozen fire' in Valyrian, and eastern 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 crafters.
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. Hilts and pommels were and are the most common decoration, for dragonglass is too brittle to make a useful crossguard. Indeed, its very brittleness is what relegates it to the great houses and the most successful merchants.
ΑΛΛΑ ΕΠΙΣΗΣ
This information seems to indicate that the elusive dagger is constructed of both known materials capable of killing White Walkers and will likely play a role in the coming war against the dead.
But that wasn't the only clue hidden in the text. On the page opposite the one that revealed there could be a massive store of dragonglass located at Dragonstone castle, there was a cut-off paragraph that suggested ingesting dragonglass may be a cure for greyscale. "Considering the only person to be cured [of greyscale] that we've heard of was Shireen [Baratheon] and the mine of dragonglass is at Dragonstone, [where Shireen grew up], it seems likely," wrote Redditor Beastmodekait.
Luckily, the only other major character infected with greyscale — Jorah Mormont — has already found his way to the Citadel. With Sam's help, there may still be time to stop the spread of his disease and give him a chance to retake his spot at Daenerys' side.
http://time.com/4860875/game-of-thro...l-dragonglass/