As a practitioner of Shin-Kendo, I am starting to be extremely irritated by the mis-information being presented regarding the use of the Daisho. The Katana is most analogous to a hand and a half sword, it's principle use being two-handed with very few cuts executed with one hand. The Wakizashi was the principly ceremonial weapon, being used mostly for ceremonial suicide, but also as a fallback weapon should the samurais Katana be unusable. Furthermore there is absolutely NOTHING wrong with Japanese iron or steel, the folding method used to strengthen the edge of the blade, however, leaves it vulnerable to damage via lateral motion, e.g. it tends to snap if sufficient force is exerted parallel to the blade (but only side to side, front or back is irrelevant).
And yes, Musashi Miyamoto would be best portrayed as a braggart and murderer, his 'unique' sword style was built entirely on the concept of deceiving his opponent and murdering them, he had a tendency to challenge samurai only when conditions were optimal for him to win as well. He was a masterless ronin who built a reputation and wealth by exploiting the code of Bushido for personal gain.
One more thing, the modern trend of making lighter weapons has nothing to do with the traditional Katana, one from the warring states period would be moderately light (5 lbs.+), but an older blade could easily mass 7-9 lbs., and I have heard from several of the sensei in the Shin-Kendo school that the higher-grade blades massed as much as 11 lbs.