Cutlass/Hanger

In the 17th and 18th centuries the cutlass was favoured by all fighting men at sea.  It's short, broad blade was the ideal weapon for hand to hand fighting on board ship - a longer sword would easily get tangled in the rigging.   According to legend, buccaneers invented the cutlass.   The long knives used by the original buccaneers to butcher meat for the boucan evolved into the famous short sword used by all seamen.
Similar to the cutlass was the hanger, the landsman's equivalent to the cutlass.  The hanger was devoloped from hunting swords and was the standard weapon of the infantryman (along with the musket).
These swords weigh around 3 pounds and are about 2' to 3' in length.

Broadsword/Cavalry Sword

Two forms of military sword commonly used by officers and some infantry.  They were not often used by sailors or pirates as their length and weight made them awkward to wield in a crowded melee on a ship's deck.
A blow from one of these was quite deadly (Blackbeard was decapitated by a blow from a broadsword!)
These swords weigh 3-5 pounds, and are around 3-3½' in length.

Smallsword

This is the sidearm and mark of the gentleman.  If you go out into "society" without one, you will suffer scorn.  However, they are not the most effective weapons in a real fight as they are too light to cause much damage, and are designed mainly for thristing.  However, this makes them ideal for duelling, which is their most common use.  The may well break if used to parry a heavier blade.
These swords weigh 1-2 pounds, and are around 2½-3½' in length.

Dagger/Plug Bayonet

The dagger was small enough for a pirate to conceal under clothes in a surprise attack, and was lethal on the lower deck where there was no space to wing a sword.   During the War of the Spanish Succesion the plug bayonet (effectively a dagger that was jammed into end of a musket barrel) was replaced in most armies by the socket bayonet (which allowed the musket to be fired and reloaded whilst attached to the musket).  This meant that there were many surplas plug bayonets, many of which were converted into very effective daggers.
Daggers typically weigh between 1 and 2 pounds and vary in length from 12" - 18".

Rapier

The rapier was generally an old fashioned weapon by the early 18th century, having been generally replaced half a century earlier by the hanger and smallsword.   Despite this, some Spaniards still chose this weapon, at least as a dress weapon.  It is certainly not a good weapon for shipboard fighting as it tends to get tangled in the rigging.  Like the smallsword they are designed primarily for thrusting and are easily broken by a heavier blade.
Rapiers weigh 1-3 pounds, and are 3-5' in length.

Boarding Axe

A popular weapon amongst pirates, helpful in boarding large vessels and climbing their high wooden sides.  Once on deck, the axe brought down the sails - a single blow could cut through ropes as thick as a man's arm.  Common on ships for fighting fires and boarders alike, it is issued to crewmen as often as a cutlass.
A boarding axe weighs between 3 and 5 pounds and varies in length from 2-3'.

Boarding Pike

The ship board version of the pike is short.   This is a common weapon on board a sip (they are often kept in racks around the base of the mast).   The head had long metal 'langets' to prevent it being chopped off.
It commonly weighs betwen 5 and 7 pounds and varies in length between 4' and 6'.

Belaying Pin

Normally, this pin is used to secure ropes.  These large wooden clubs are found all over a ship and are often used as a weapon.  Usually made from a dense hardwood such as lignum vitae they do considerable damage when used as a club.  They are often used by press gangs.
They typically weigh 3-5 pounds and vary in length from 1-3'.

Flintlock Musket

Although full sized land muskets were used at sea (especially by ex-privateers and warships) they were not as common as musketoons and blunderbusses, though they were the standard weapon of infantrymen.  The flintlock had replaced the matchlock as it was more reliable in wet weather and faster to reload.  Although standard military muskets were smoot-bore, some gentlemen used rifled muskets for hunting.  These are far more expensive than smooth bore muskets, and take much longer to reload, but the are more accurate at longer ranges.  However, a marksman needs very calm seas for careful aiming onboard a ship.
Thet weigh around 14-20 pounds and vary in length from 4-5'.

Matchlock Musket

If fancy new stuff does not impress you, this is your weapon.  It perform poorly in wet weather and is slower to load and ready than a flintlock.  Fairly old-fashioned by the early 18th century, matchlocks have the advantage that they are cheap and easy to repair, although they are heavier and more cumbersome.
Matchlocks weigh between 18 and 25 pounds and vary in length from 4½-6' in length.

Flintlock Carbine

This is basically a shorter version of the musket.  Although not as accurate at longer ranges, it is comparable at closer range, and it is easier to handle than a musket.  Carbines are common amongst Dragoons (mounted infantry).
A carbine weighs between 8 and 12 pounds and is around 3-4' long.

Musketoon

The short barrel of the musketoon limited its accuracy, so it was only used at close quarters.  Usually loaded with multiple pistol bullets that spread as the shot travelled.  Like the musket, it was fired from the shoulder, but the short barrel made the musketoon easier to handle on a cramped, pitching deck on the high seas.
A musketoon weighs between 9 and 15 pounds and varies in length from 2-3'.

Blunderbuss

This brutal, shotgun-like weapon is most effective against boarders.  The blunderbuss is a short range weapon, firing a cluster of pistol balls, nails, scrap iron ot just about anything else in a wide, short range burst.
A blunderbuss weighs between 10 and 16 pounds and varies in length from 22-32".

Pistol

Lightand portable, the pistol was the pirate's favourite weapon for boarding.  Reloading was so slow that pirates often didn't bother, preferring to use the gun's hard butt as a club.  Successful pirates often carried several pistols (Blackbeard reputedly carried 6 and Bartholomew Roberts carried 4, as well as swords and daggers).  Pirates often tied their pistols to their belts with silk cords to avoid dropping them overboard during a fight. 
Large, sea service pistols (bottom pictures) weighed between 4 and 6 pounds and varied in length from 10-18".    Smaller 'Queen Anne' pistols (top) weighed between 3 and 5 pounds and varied in length from 6-10", but did less damage.

Grenade

These clumsy little bombs are unjustly feared by soldiers and gentlemen alike.  Although the military used iron grenades which explode in a cloud of fragments, most pirate grenades used simple ceramic shells.   Their fuses do not always burn at rhe same rate (especially in tropical climates like the Caribbean).  This allows them to be thrown back on occasion (by the daring victim).  Pirates often used a ceramic greanade, stuffed with tar and rags rather than explosive, creating a smokescreen of confusion and panic.
A grenade weighs around 2-3 pounds and looks like a roundshot or clay pot with a fuse sticking out of it.

Swivelgun

Swivelguns (so called because they were mounted on swivels on the ship's gunwales) are like minature cannons and were generally loaded with grapeshot.  They were used to sweep the deck of an enemy ship before boarding.
Swivel guns are more lightly constructed than cannon, and tend to weigh about 50 times the weight of the shot.  They come as 1-, 2- or 3-pounders.   The weight of powder needed was approximately half the weight of the shot fired.

Cannon

In the early 18th century, even the smallest merchant vessel carried artillery pieces (guns).   To be correct, a cannon referred only to a specific size and type of ordnance, although the term is generally applied to all guns mounted on carriages.   By the late 17th century, cast-iron had replaced bronze as the most common material used to manufacture ordnance, making guns cheaper and easier to produce than before.   The wars of the late 17th and early 18th centuries meant that arming a vessel was a necessity.   It also meant that most sailors were proficient to some extent in operating guns at sea.

A four wheeled truck carriage was universally adopted by the late 17th century, which allowed the cannons to be rolled easily back for reloading.   Naval gun carriages were much heavier than those of land guns as they didn't have to be pulled around by horses!   The simple but effective elevating system of quoin and stool bed was efficient enough for use at sea.   Gun tools such as worm, rammer, sponge and ladle were kept beside each gun, ready for action while powder charges were brought up from the ship's magazine.  A typical gun required a crew of three or four men to reload and fire, a process taking two to three minutes for a trained crew (even longer for big shore guns).   A 4-pounder, the typical gun size on a sloop or small schooner, could fire a roundshot about 1,000 yards.  However, long range artillery fire played a very small part in naval warfare.   Cannonballs did little damage at long range, and cannon fire was highly inaccurate.   No two guns - or cannonballs - were exactly alike, and gunpowder also varied.   The loose-fitting balls did not emerge on a true center line, and the recoil changed the setting at each firing.   There were no sights, and guns could not be traversed from left to right.  Although  most guns could reach several thousand yards, the maximum effective range was 200 to 500 feet. 

Ships' cannons are given in poundage, referring to the weight of the shot that it fires, the gun itself usually weighs around 200 times the weight of the shot it fires; a 10-pound cannon weighs some 2,000lbs, but fires a 10lb ball.   Cannon come in 2-, 3-, 4-, 6-, 8-, 9-, 10-, 12-, 14-, 16-, 18-, 20- and 24-pound varieties, though those over 16-pounders are only found on Naval vessels.  (Shore forts often boast heavier guns, 32-pounders being common, and some as heavy as 68- or 72-pounders, but these were not used on board ships at this time.)   The weight of powder needed was approximately half the weight of the shot fired.

Caltrop/Crowsfoot

Pirates sometimes tossed caltrops or crowsfeet onto the deck of a ship they were boarding.  Since sailors usually worked barefoot to avoid slipping on wet decks, the spikes could inflict terrible injuries if trodden on.