The other thread is in danger of getting overwhelmed by the focus on sword talk and considering the theme of L5R, I bet that other threads are at risk of highjacking as well. Not that anybody intends to do so, it is just going to be a natural progression of discussion!
This will be a good place to keep all the discussions, arguments and theories as to the katana; both the historical facts of the sword in Japan and the place the sword should have in an RPG set in Rokugan.