Meito

A Meitou is not a type of sword but rather the status of a sword.

In Japan, this means the sword has a history and is of legendary status. The blade is normally a quality blade which stands out above all other swords in its endurance and sharpness.

A Meitou is sometimes associated with the warrior who wields it and becomes part of his identity. Regardless of who owns them a Meitou is regarded with highest respect in Japan and to be given a Meitou is to carry a great honour alongside it. Often warriors who lost in battle would have their Meitou taken from them by the victor, thus loosing their honour alongside it as to loose a Meitou is to disrespect the honour of wielding it.

To steal a Meitou or gain it using another dishonorable action is to show the Meitou disrespect and warriors who do so were often frowned upon. To put the status of a Meitou in a western style of thinking, a Meitou to would be considered in status on par with swords like Excalibur.

One Piece
In One Piece, Meitou is often mistranslated as either part of the name of a sword(e.g. Zoro's Shuusui which is often recorded by fans as "Meitou Shuusui" instead of just "Shuusui" in error by those who do not understand that Meitou is a status) or as a "named blade"(understandable given that if you break up 名刀 it forms 名 for name and 刀 for sword.) The latter is more accurate but still incorrect as any blade can have a name, but only a few swords are Meitou.

Tashigi's dream is to free all the Meitou from the hands of villains such as pirates. She believes the swords are crying because instead of being used for noble and honourable deeds, they are being used for criminal use. Her reason for tracking Zoro is to gain ownership of his Meitou, the Wadō Ichimonji which she believes is in the hands of a bad person. As of Chapter 541, she has no victories over Zoro in her quest and as far as we know, none of the other Meitou in her journey of Justice.

List of Meitou

 * Wadō Ichimonji was Kuina's family Meitou and Zoro was allowed permission to wield it as part of their promise to each other and carry to with it her dreams. Zoro tends to keep this sword in his mouth and apply it for his steel cutting techniques besides his frequent use of it in Santouryu situations where he is forced to use one sword. It is the only sword that Zoro has had from the beginning of the series and never got broken.


 * Ryuuma's Meitou was his sword Shuusui which belongs to Zoro now. Upon defeat, Brook's shadow offered it to Zoro as a sign of honor for their battle and because he shamed the Samurai it inhabited by losing to Zoro. It appears to be a cursed blade as well as Zoro compared it to "a child" yet he was able to hold back Oz alone with the blade despite strongly implying he isn't capable of using it's full power.