Cutlass were an extremely popular weapon for pirates in the time.
A cutlass.
It was slightly curved and single-bladed, it's purpose was not for fencing with your victim, but hacking at him. Edward "Blackbeard" Teach cut off Robert Maynard's sword and almost stabbed him, but Teach was killed by one of Maynard's crewmen with a cutlass by a slit of the neck.