It is a Ken.
I last saw it many years ago and read Akutagawa's stories at about the same time, but somehow I recall that the bandit lures the samurai deep into the forest to show and sell him Korean-style weapons from a tomb. Well, the Hyunday was a lemon
If it sounds too good to be true, it probably is
How about the "Samurai" trilogy, also with Mifune?
And, of course, the Polish trilogy: Deluge, By Fire and Sword and Pan Volodyewsky?
And, again, if you want to see swords, yataghans and kilijes galore, find an old Russian movie " The Sword and the Dragon" ( Real title was "Ilya Muromets"). Kievan Rus against the Tatars.