In a society with a strong concept of honor, both men would use similar weapons. If one was lacking such a weapon, the other would provide it before the fight started. That's what 2 Samurai would do. And why? Mutual respect, that's why.

But I am talking in very idealistic terms here, so feel free to raise your eyebrows in disbelief, as I realize the present age of human development is completely unfamiliar and out of sympathy with such concepts. The only thing that counts now is "winning"...and that's an ethic that at heart I despise. It's completely unworthy of the warrior credo.

Within the context OF an Indiana Jones tale, though, it worked fine for him to shoot his opponent and I have no objection to the scene. It fits the movie perfectly.