I thought it was a wine glass, with some kind of symbolsim with regard to the spear and the "love bikini" markings.
I searched and found this:
BLACKBEARD: Ocracoke's Most Famous Visitor
Piracy was as much a state of mind as an occupation. Pirates built upon their reputations with actions and symbolic gestures. Flags were an important part of creating the total pirate image. Blackbeard's flag depicting a heart dripping blood while a skeleton held an hourglass and spear, was designed to strike fear in the hearts of his victims.