Originally Posted by Riou
A German ZweihÃ¤nder two-handed long sword is almost 6 feet long.
One version of the ZweihÃ¤nder is 7 feet long. Ridiculously long swords have been used throughout European history.
In Japanese culture, it was not entirely unusual to have swords between 65-70 inches (~1.8m) in total length.
While an Ōdachi was not commonly used in the later periods of Japanese warfare, when combat was often done in open fields, it's believed that they were used both on horseback and on foot.
The idea behind creating a sword is either:
- To make it light enough to wield easily.
- To make it heavy enough to damage someone wearing armour.
If you're going to use a sword in a single hand, you want the first. If you're going to use it in two, you want more of the second.
(obviously, you want a mix of both at all times. Don't get me wrong...)
If you can put two hands into the swing of a sword, you instantly have more force, and the longer it is, the more (turning) force you impart, treating it almost as a lever - as the far end will swing faster (think of it as if it were a wheel, where the outside spins faster than the inside).
Basically, if you can still swing it, longer is generally better. The more distance between hands would also allow you to potentially impart more force by using one hand as a fulcrum (pivot) to give more weight to the strength of the other - potentially making the use of a weaker left hand palatable to someone unused to swinging something so heavy.
... The problem with all of that is that you must factor in the character's real strength, and games often go overboard with just how long a sword a person can carry. If you are going to get truly worn out swinging it, for most military purposes, it would have been useless. Battles often lasted twelve hours, and if you couldn't fight solidly for at least six swinging it almost constantly, you were not going to be a very good infantryman.