Pirates would use whatever swords and daggers they could lay their hands on, usually stolen.
However, the highly sought after weapon of choice was the cutlass. For a pirate, it had many advantages over regular swords. It had quite a short blade which meant it didn't get caught or snagged in the rigging onboard a ship, which is where most of their fighting took place. It also had a very wide and heavy blade, which made it good for fast and brutal hacking and slashing. Definitely not a delicate and subtle fencing type weapon. If you get hit by one of these, you stay hit. 😁
This example is my trusty Windlass blade, which has seem me through many a fight and ensured the I have kept all my fingers.
@nigelrogers We are not allowed to carry our swords or guns on the street. but can use them in designated performance areas. The local Police are aware of our re-enactment status and they know we are a charity fund raising group. So, they do grant us a fair bit of leeway to transport our weapons to and from events. In fact we do have a very good relationship with the Devon and Cornwall police.