A cutlass was a type of sword with a curved blade.
Amy Pond once used a cutlass to fight the entire crew of the Fancy when they wanted to make the Eleventh Doctor walk the plank in 1699. (TV: The Curse of the Black Spot)
The Tenth Doctor described himself as a "dab hand with a cutlass" when he used one to an amnesiac Jackson Lake from two Cybus Cybermen during the 1851 Incident. (TV: The Next Doctor)
The mad Sontaran colonel Snathe owned a cutlass which he almost used to behead the Tenth Doctor. (COMIC: The Betrothal of Sontar)
Pirate Sea Devils used cutlasses used cutlasses with hexo-toxic poisoning. (TV: Legend of the Sea Devils; GAME: Worlds Apart [+])