Swords

A sword is a long edged weapon, used in many forms by various civilizations throughout the world. The word sword comes from the Old English sweord, which cognates to Old High German swert, Middle Dutch swaert, Old Norse sverð, Swedish svärd, Old Frisian and Old Saxon swerd and Modern Dutch zwaard, from a Proto-Indo-European root *swer- "to wound, to hurt".

A sword fundamentally consists of a blade, with one or two edges for striking and cutting, a point for thrusting, and a hilt for gripping. The basic intent and physics of swordsmanship remained fairly constant down the centuries, but the actual techniques varied among cultures and periods as a result of the differences in blade design and purpose. The names given to many swords in mythology, literature, and history reflect the high prestige of the weapon.

Swords in One Piece and their Classifications
Swords are a very common weapon in the world of One Piece. Many people wield swords, but there are those who train hard, and learn to use swords exceptionally well. These people are known as swordsmen. Throughout One Piece various Swordsmen come in different grades and types. Some of these swords they wield are named and are even classified as "meitou".

Katana
The katana is a type of Japanese sword. It is a single-edged, curved blade that was used by many samurai. Pronounced as "kah-tah-nah", both katana and katanas are acceptable as the plural forms. Tashigi's Shigure is a katana.The katana length is between 90cm and 1m.
 * For further information, see Katana

Daitō ("Long Sword")
Rather than a specific weapon, the daito is actually a category of blades under which both the katana and tachi fall. To qualify as a daitō the sword must have a blade longer than 2 shaku (approximately 24 inches or 60 centimeters) in a straight line. In the case of Roronoa Zoro, all three swords that he uses for his Santoryu are all confirmed as Daito katanas.
 * For further information, see Daitō

Nodachi ("Field Sword")
The nodachi is a large two-handed Japanese sword. Compared to the katana, the nodachi was more difficult to wield due to its size and weight, but - like any weapon - could be extremely deadly if the warrior wielding it was skilled. The length of the nodachi's hilt varied between twelve to thirteen inches (30 to 33 centimeters). Its cutting capability and range exceeded that of a katana, due to its weight and size. The captain of the Heart Pirates, Trafalgar Law wields one of these, to be used in conjuncture with his Devil Fruit powers. Shiryuu, former Chief Guard of Impel Down, also wields one.Nodachi's length can reach the 1.50m.
 * For further information, see Nodachi

Cutlass
A cutlass is a short, thick saber, with a straight or slightly curved blade sharpened on the cutting edge, and a hilt often featuring a solid cupped or basket-shaped guard. Best known as the sailor's weapon of choice, the naval side arm, likely because it was also robust enough to hack through heavy ropes, canvas, and wood. It was also short enough to use in relatively close quarters, such as during boarding actions, in the rigging, or below decks. Many low-ranking Marine soldiers and pirates are shown to be wielding one of these.
 * For further information, see Cutlass

Saber
A saber is a type of sword with a single edge blade with a large hand guard. Its blade is usually (but not always) curved of variable length. Unlike a cutlass, the saber is longer and thinner in design. Sabers are often seen being used by background characters. The most notable use of one is by Shanks, who seems to favor them over other sword types. His saber seems to be larger than a normal one.
 * For further information, see Saber

Kukri
The kukri is a heavy, curved knife used for both as a tool and a weapon. It is slightly deflected at an angle of 20°, though some examples have a very steep angle. The kukri starts with 3 to 10 centimeters, the length is 30 cm onwards, tapering towards the edge from the broad upper margin. It almost always has a single edge and almost never has a "false edge". It usually has a very thick spine and in many ways is a hybrid between knife and axe. The "Big-Knife" used by Sarquiss resembles a kukri, and Helmeppo uses two kukri for combat.
 * For further information, see Kukri

Shikomizue
A shikomizue (Japanese prepared cane) is a sword normally concealed inside a cane or walking stick. It became popular when katanas were outlawed. Brook has been seen wielding one for his Fencing Style, and Roronoa Zoro also used one in an anime-only flashback.
 * For further information, see Shikomizue

Saijō Ō Wazamono Grade Swords
There are 12 Saijō Ō Wazamono (Supreme Grade Sword). These seem to be the highest quality swords.

Known Swords

 * Kokutou Yoru
 * Shodai Kitetsu

Ō Wazamono Grade Swords
There are 21 Ō Wazamono (Great Grade Sword). Their quality is one step lower than the Saijō Ō Wazamono.

Known Swords

 * Nidai Kitetsu
 * Wadō Ichimonji
 * Shuusui

Ryō Wazamono Grade Swords
There are 50 Ryō Wazamono (skillful grade sword). Their quality is higher then the Wazamono but lower then Ō Wazamono Grade Swords.

Known Swords

 * Kashū
 * Yubashiri

Wazamono Grade Swords
The Wazamono Grade Swords are sharp swords, and the lowest grade possible for a named blade.

Known Swords

 * Sandai Kitetsu
 * Shigure

Swords with Unknown Classifications
Note: These swords are not listed by strength.
 * Arlong's Kiribachi (a cross between a saw and a zanbato)
 * Seven Stars Sword (somewhat like a katana)
 * Ohm's Sword (a katana-shaped sword with shape-shifting abilities)
 * T-Bone's Sword (a broad sword)
 * Funk Freed (a Western-curved sword that can change into a elephant)
 * Kaku's Swords (a pair of katanas with simple wooden handles)
 * Helmeppo's Swords (a pair of kukri)
 * Shanks' Sword (a large saber)

Knives
A Knife is a small single bladed tool used for cutting things with. A knife has come to be seen as a eating tool, but it can be used for many things. Because of their size, they are easily concealed and can be used as weapons for fighting with.

Sanji has been seen using knives for cooking as well as calling them a chef's soul. Buggy carries many knives with him, including hidden within the soles of his shoes. Other pirates and people carry knives for combat or other purposes.