I would recommend you look at this post for more information about weaponry used by pirates: Which weapons did pirates use during the Golden Age of Piracy (1650-1730)?
None of the swords used at sea during the GAOP would be described as sabers, but that's besides the point of your original question. For machetes, if they didn't have any other swords, they would use one if they had one. They are very similar to cutlasses to begin with, but machetes lack guards on the hilt, a significant disadvantage compared to cutlasses or other swords built for combat. In the published account of the trial of Anne Bonny and Mary Read, the exceptional cases of female pirates in the GAOP, one witness mentions seeing the two women wielding machetes and pistols.