Other reviewers said all that needs to be said about the qualities of this wonderful film. I will just cover a plot detail which can easily be overlooked, but which reveals just how intelligent the story really is. That detail is the "hidden blade" itself.
When the duel ends, the dying Hazama is pained by two things: that our hero Katagiri did not condescend to use the secret technique of the Hidden Blade against him; and that their master taught the technique to the inferior pupil. In fact, it is confirmed twice during the film - first by Katagiri and then by Hazama - that Hazama would have won their mock duels in the past if they had fought with real blades. Hazama was the better swordsman of the two, but he wasn't allowed to learn the Hidden Blade. Why?
We see the Hidden Blade at the end of the film, when Katagiri uses it against his superior, who was a scoundrel. We understand that the Hidden Blade is not a fighting technique, but a murdering technique. It cannot honorably be used against a samurai in a fight. That explains why he didn't use it against Hazama.
OK, but why didn't their master teach Hazama the Hidden Blade? The answer is simple: that technique has nothing to do with who is a better swordsman. Since it is so deadly, it can be taught only to a person who will not abuse it, a person of integrity. And Hazama was never such a person.
In this way, the ending cleverly ties all the loose ends of this great film.
When the duel ends, the dying Hazama is pained by two things: that our hero Katagiri did not condescend to use the secret technique of the Hidden Blade against him; and that their master taught the technique to the inferior pupil. In fact, it is confirmed twice during the film - first by Katagiri and then by Hazama - that Hazama would have won their mock duels in the past if they had fought with real blades. Hazama was the better swordsman of the two, but he wasn't allowed to learn the Hidden Blade. Why?
We see the Hidden Blade at the end of the film, when Katagiri uses it against his superior, who was a scoundrel. We understand that the Hidden Blade is not a fighting technique, but a murdering technique. It cannot honorably be used against a samurai in a fight. That explains why he didn't use it against Hazama.
OK, but why didn't their master teach Hazama the Hidden Blade? The answer is simple: that technique has nothing to do with who is a better swordsman. Since it is so deadly, it can be taught only to a person who will not abuse it, a person of integrity. And Hazama was never such a person.
In this way, the ending cleverly ties all the loose ends of this great film.