Great topic, and wow at
@Yora's lengthy post, really informative!
I have little to contribute in regards to this question. I know of a particular mistake that is done in videogames and movies with fight scenes using swords, and that is to have two blokes crossing their blades for a long time. Especially when it comes to the Japanese Samurai, they trained to be able to kill / defeat their opponent with as few strikes as possible, to keep the blade sharp - it actually gets blunt faster than most people think.
As for the Portuguese-Japanese interaction question raised off-topic, I am no expert in that matter. The Katana word actually made its way from Japan to Portugal, and there's some debate as to whether the Japanese for 'Thank you',
Arigato, comes from the Portuguese
Obrigado, which sound very similarly. The Portuguese Jesuits were also the first real propagandists for the spread of Christianity in Japan, and the first to present a Gunpowder weapon to the archipelago. Oh, these were also the first Europeans to bring tea back to the West from Japan, so yeah, you owe us that my British friends
Unfortunately, I know little more than this - I have always focused on the study of Islam, and so am more familiar with Portuguese relations with Northern Africa, Middle-East and India at the time of the Mughal Empire
