During what is commonly referred to as the Golden Age of Piracy, the early 18th century, or "the Pirates of the Caribbean time", pirates were often armed. This is not surprising as they are criminals who take things by force. It may be, in fact, silly to think of them without weapons, as their weapons have become a part of their costume, so to speak. This is a short study of the common personal weapons that pirates most often used. Please understand that this is not meant to be an exhaustive list. Clearly weapons such as hammers, marlinspikes, whips, flails, and garottes could and I'm sure did come into play. Yet, those were not the common weapons of pirates, but rather the weapons of convenience. Knives, swords, axes, and guns were the common weapons of the time.
Knives
The most common weapon was the knife because it was also a tool of both hunters and sailors, which is where Buccaneers came from. Knives were also commonly used because they're small and easy to carry concealed -or- between your teeth whilst climbing up the side of a ship that you're about to attack. Quick and quiet, knives made the best weapons for taking a ship in the dead of the night. Versatile, as they can be thrown, used to puncture or slash, plus lightweight and easy to carry. It is easy to see how the knife was clearly a pirate favorite.
(More pics of this great knife can be seen at http://www.britishblades.com/forums/showthread.php?38165-A-Pirates-knife-yo-ho)
Cutlasses
Pirates also used swords. The most common type of sword used by Pirates during the Golden Age of Piracy was the cutlass. Their short, heavy blades sharpened only on one edge made excellent machetes and shipboard tools, as well as weapons. The reason for this design was the use of the weapon; dual-edge swords can cut on both the forward swing and the back-swing. There is much less control on the back-swing and an accident could mean damage to the sails and sheets of the ship. It was true that some sailors and pirates used rapiers. This was rare however, because the rapier is primarily a thrusting weapon and it takes great skill to master. The rapier is the weapon of a duelist, not a murderous thug.
Boarding Axes
One of the most common weapons, or tools, found on ships of this period is the ax. Most sailors probably thought of the ax as more of a tool, like a fireman's ax, than a weapon. No matter, as the ax makes an effective boarding weapon whether you choose to attack your enemy directly or damage their ship. Many of the French buccaneers used a small hand ax, not unlike the tomahawk, as an offhanded weapon. Additionally, every ship of the period should have AT LEAST 1 ax to cut away storm-damaged pieces of rigging and to cut wood for repair pieces.
Belaying Pins or Clubs
The belaying pin is a piece of hard wood or brass 18" - 24" long in a pin or baton shape that fits into a set of parallel holes, one above the other, in the rails or around the masts. It is a tool on board a sailing vessel of this period that performs the same duty as the modern cleat; it serves as a place to "make fast" or tie off lines from the running rigging (that's the part of the rigging that moves). As each sail could have as many as 6 running rigging lines coming from it and each line needs a place to be tied off, you begin to see how there are many pins along the rails on both sides of a ship with 15 or more sails, as most vessels with 3 masts could easily have.
Pistols
From the Fifteenth century and the arrival of the Spanish in the Caribbean, pistols became the premier personal weapon. They were highly prized by pirates. In some ship's articles, it was agreed upon by the entire crew that the lookout who spotted a ship that ended up as a prize got the choice of the pistols found aboard. Unfortunately, despite their incredible popularity both in history and in fiction, pistols of this time period are neither accurate, nor reliable. This is especially the case when mixed with the humidity of the Caribbean region. Simply put, black powder weapons absolutely require dry powder to fire properly and it is incredibly difficult to keep powder dry in a place where the air is saturated with water.
Of course as the centuries roll by, black powder becomes more stable and the mechanisms of the pistols become better as well. Even so, pistol shots at close range still failed nearly a third of the time. Again, we must consider the pirate and remember his goal is usually thievery. Pistols, especially a number of them, are intimidating all on their own. A pirate might be able to convince common people to help him just by intimidation without ever having to threaten them directly. How comfortable would you be around a terrorist covered in weapons, which is roughly the equivalent of how people of the 18th Century viewed pirates at that time.
Long Rifles
It is interesting to note that although the British and French were known to use long rifles from the rigging (or more accurately from the fighting tops), the Spanish never did -- their Admiralty believed that the risk of fire in the rigging far outweighed the benefits of guns. Even as late as the 1700's, the Spanish used bows and crossbows in their fighting tops.
Blunderbusses
If the long rifle was the assault weapon of the period, then the blunderbuss is like an AK-47 with undermounted grenade launcher. This weapon was 100% intimidation; 3 - 5 people standing in its explosive path would become the blood red paint that covered the people behind them. It was a terror weapon. It was used both to intimidate and to end boarding actions. If there were 4 of these side by side, they would clear a deck. Blunderbuss, when you absolutely want to make it clear that you are in charge and you are not afraid to redecorate in arterial red to prove it.
You can see more of this glorious piece at the following site.
http://contemporarymakers.blogspot.com/2009/12/brass-barreled-blunderbuss-by-david.html