In reading Samurai-Archives.net, I've been reading where katana or any sword was a secondary or better yet, quaternary weapon in the hands of a samurai - at least until after the warring period was over. Before the Tokugawa Era/Edo Period - the great peace that lasted from the mid 1500's until 1868, the katana was given barely a thought except in dueling situations.
The primary weapon of the samurai was the bow. Next came the naginata spear, then arquebus, and finally katana. Even then a tanto dagger was a preferred close combat weapon over even the katana.
When Tokugawa Ieyasu - the founder of the Tokugawa Shogunate, declared the katana as the 'soul of the samurai', it was really more a statement of propoganda. Conferring to samurai the katana as a symbol of office and caste, not as a weapon of war.
Japanese armies need bow, naginata and arquebus to instigate war and win them. The katana is an officer's weapon, little more.
GP