A bo-hi (also spelled 'bohi,' 'hi,' 'fuller,' or 'blood groove') is a groove in the blade placed directly behind the spine that helps to reduce weight without sacrificing durability. They are commonly found on folding knives made before the advent of stainless steel, when aluminum was used instead.
Katana had these grooves also. However, they are not present on all katanas. You can see from this image that the back side of the blade is completely smooth:
Image courtesy of http://www.foldingknife.com/
Even though it's not visible in this photo, most katana blades were actually double-edged, meaning they had a sharp edge on both sides of the blade. This allows you to use either edge for slashing and stabbing actions. A single-edge knife is more suitable for detailed work like filleting because you want only one cutting surface to keep track of. There are some exceptions such as the yokoto, which was usually only equipped with one side of the blade; but even so, it was still considered offensive weaponry.
So yes, Katana had bo-hi on their blades too. But not all ones did. And since this is true, it means that Mr. Miyagi didn't invent anything new when he made his knife.
The hi, also known as the bo'hi, is a groove in the blade positioned slightly beneath the spine. Many people misunderstand this groove, as well as the fuller on the European blade. The "hi," like the fuller's goal, is to lighten the blade while sacrificing as little strength as possible....
Odachi and nodachi are abnormally long blades (longer than three shaku), generally carried across the back. The term odachi is also sometimes used to refer to Japanese swords. Odachi means "huge sword," whereas Nodachi means "field sword."
Long swords were not common in Japan during medieval times; rather, they were used by elite soldiers called samurai. A samurai would carry his sword in two forms: as a tsuka (handle) with a sharp blade attached, or as a zweihander (two-handed sword), which was double the size of a tsuka. Because they were so rare, expensive, and prestigious, these swords were often preserved and handed down through generations of families.
There are some myths about how long a sword should be. One myth says that a sword should be at least 1 meter (3 feet) to be considered odachi. However, this is not true because any sword can be longer or shorter depending on who is using it and how they plan to fight with it.
Another myth is that an odachi must have a thin blade because it's such a powerful weapon. But this is also not true because many other types of swords exist with thick or thin blades.
In conclusion, an odachi is a long sword but it does not need to be exactly 1 meter long to be called such.
The Dai Katana is a latex-hybrid sword with a squared guard that has a striking Asian aesthetic. The sword is 100 cm from tip to pommel and has a 70 centimeter slim, single-edged blade. While on the battlefield, the long, detailed handle accommodates two hands and a sturdy, comfortable grip. The sword's name comes from the Japanese word dai, which means big or large. The katana was originally used in combat between 14th century Japan and 16th century Japan.
A samurai warrior needed a sword that was strong and reliable. At the same time, he wanted something that looked impressive when worn on the battlefield or during ceremonial events. The Dai Katana fits this description perfectly because it is long and slender, like the samurai himself. Also, due to its unique design, the sword can be wielded with great effectiveness both on foot and on horseback.
According to some historians, the first samurai appeared around 10th century Japan during the Heian period. These warriors served the kings of Japan and protected them by using their swords against enemies who had been sent by the king to kill him. The role of the samurai changed over time as the country transitioned from being a monarchy to a democracy. Today, they are often associated with Edo-period Japan (1603-1867).
Mounted samurai began to favor the katana in the fourteenth century, as they frequently dismounted for hand-to-hand battle. The wakizashi, a shorter companion blade, quickly joined the katana in the samurai's inventory. The two were known as daisho when worn together (big and little). When used by themselves, they were called goken (foresword and backsword). Miniature versions of the katana called chodachi have been found buried with their owners at many sites throughout Japan.
Why did Samurai wear armor? Armor was expensive and heavy, so only rich people could afford it. Also armor made fighting from horseback more difficult which means you needed good horses. Finally armor helped protect against arrows and other weapons used by enemies.
Who was the best swordsman in film history? This is quite a hard question to answer as there have been so many great swordsmen over the years but if I had to pick one person it would be Toshiro Mifune. He was a Japanese actor who became famous all around the world for his role as a samurai. Not only was he an amazing sword fighter but he also played many other roles over the course of his career which makes him even more impressive. He was first and foremost though a great actor who happened to use a sword very well when necessary.