The Demon Hunter's Handbook is a book by Abelard Van Helsing which gave advice on the slaying of all of the spawn of the Pit, including Dragons. They are ancient, rare and can slumber for centuries.
To Slay Dragons
Dragon Bone Daisho Swords
Blades which can slice through Dragon flesh. Also, if crossed diagonally in front of the wielder, they can deflect Dragon flame. The handles of Abelard's swords were forged from the slain Wyvern Gilgrim, which had terrorised a Japanese village for many years, by master craftsman Masamune. One sword, the katana is long while the other, the wakizachi,is short.
Don't bother. Your speed is the most important thing.
The wing membrane can be hurt, which will unbalance the dragon. Also, the eye and the armpit are unprotected
The Dragon Hunter's Handbook