Odachi Swords - More Info
An Ōdachi is a big Tachi (also called a nodachi). To be considered an Odachi, the blade needs to be over 3 shaku (90cm). While the extent of their use in battle is unknown, we do know they were used in ceremonies, as symbols of status, and as offerings to gods.
Due to the size of Odachi (nodachi), they were likely used on the battlefield as primary weapons. Because of their exceptional length, they would have shined as horseback weapons. The longest example of an Odachi still in existence is the Norimitsu Ōdachi , which measures over 12 feet long! Such ridiculously long blades were not used in battle, but as exhibitionary pieces for the most talented swordsmiths or as offerings to gods.