The Dragon Sword was the prototype for the black sword, and served as a container for the she-dragon that would give birth to the brood of the phroon. Who would be the mernii's ancestors. It was forged by chaos to conquer chaos. It didn't belong to Prince Flamadin or John Daker. It was from the remains of it that Stormbringer was made. Along with Mournblade. The difference being that instead of said she-dragon the Anti-Balance was sealed inside of them. The chaotic half of it. Whereas the lawful aspect was sealed in the black pearl.