Ōdachi An ( large / great sword ) was a type of long traditionally made Japanese sword ( nihonto ) used by the samurai class of feudal Japan . The term nōdachi ( field sword ) refers to the same type of sword . The character for " ō " ( 大 ) means " big " or " great " . The characters for " da " ( 太 ) and " chi " ( 刀 ) are the same as " tachi " ( 太刀 , lit . " great sword " ) , the older style of sword / mounts that predate the katana . The " chi " is also the same character as " katana " ( 刀 ) and the " tō " in " nihontō " ( 日本刀 " Japanese sword " ) , originally from the Chinese character for a blade , " dāo " . To qualify as an ōdachi , the sword in question would have a blade length of around 3 " shaku " ( 35 . 79 inches or 90 . 91 cm ) however , as with most terms in Japan ese sword arts , there is no exact definition of the size of an ōdachi . Purpose . Practically speaking , the function / use of most ōdachi fall into the first two categories — as ceremonial objects and cavalry swords . The possible functions of the ōdachi can be categorized as follows : Production . Ōdachi are difficult to produce because their length makes heat treatment in a traditional way more complicated : The longer a blade is , the more difficult ( or expensive ) it is to heat the whole blade to a homogenous temperature , both for annealing and to reach the hardening temperature . The quenching process then needs a bigger quenching medium because uneven quenching might lead to warping the blade . The method of polishing is also different . Because of their size , Ōdachi are usually hung from the ceiling or placed in a stationary position to be polished , unlike normal swords which are moved over polishing stones . Acquiring a fully sharpened Ōdachi would be hard as they would almost certainly have to be custom - made . They are still made on occasion . One such sword , made in 1971 , ( now in a private collection in Texas ) was made at the request of a dying man . Its purpose was to please the gods and enlist their protection of his family after his impending death . Method of use . Ōdachi that were used as weapons were too long for samurai to carry on their waists like normal swords . There were two methods in which they could be carried : One method was to carry it on one ' s back . However , this was seen as impractical as it was impossible for the wielder to draw it quickly . The other method was simply to carry the ōdachi by hand . The trend during the Muromachi era was for the samurai carrying the ōdachi to have a follower to help draw it . Ōdachi swordplay styles focused on downward cuts and different wields than those of normal swords . Reasons for loss of popularity . The ōdachi ' s importance died off after the Siege of Osaka of 1615 ( the final battle between Tokugawa Ieyasu and Toyotomi Hideyori ) . Since then , it has been used more as a ceremonial piece . This loss of popularity is due to : After the law was put into practice , ōdachi were cut down to the shorter legal size . This is one of the reasons why ōdachi are so rare . Ōdachi were no longer of practical use , but were still made as offerings to Shinto shrines . This became their main purpose . Due to the amount of skill required to make one , it was considered that their exotic appearance was suitable for praying to the gods .