Arrrr I seen that sword with me own two peepers. Swung around it did back on that old crazy cook beardblack. It looked like a black cat crossing me path, only alot larger, and it wasn't a cat. They all called me crazy, and maybe they be right, but I seen that sword.
To be more serious, I somehow doubt this was Blackbeard's sword. Okay, it was on his ship. It was in pieces and abandoned there, though. That doesn't seem like something a person would do with their sword. More likely it was some loot from a raid.