Interesting to say the least. Though for some reason I doubt it was Blackbeard's. Traditionally in those times when someone was defeated they surrendered their sword, or at the very least it was taken from them. Then again, Blackbeard could have had several swords and this just one of them that was in his room and subsequently not taken. I guess no one will really know. Not like we can take fingerprints or DNA for testing.

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"BOY: On a hot summer night, would you offer your throat to the wolf with the red roses? GIRL: Will he offer me his mouth? BOY: Yes. GIRL: Will he offer me his teeth? BOY: Yes. GIRL: Will he offer me his jaws? BOY: Yes. GIRL: Will he offer me his hunger? BOY: Yes. GIRL: Again, will he offer me his hunger? BOY: Yes! GIRL: Yes. BOY: On a hot summer night, would you offer your throat to the wolf with the red roses? GIRL: Yes. BOY: I bet you say that to all the boys!" -Meatloaf