He also dreamed up a revolver.Well, there was that bit where Sulu dreams up a samurai while on the 'short leave' planet. This plays into his Japanese heritage. If Sulu was a white guy and a samurai was dreamed up, I would expect the episode to tell us why that happened for that particular character.

It was already hinted that he had an interest in old Earth weapons, like the saber (e.g. "The Naked Time"). Not too mention, Sulu, the character is Asian-American...even though it's established he was from San Fran in the 4th film. Too, his excitement finding the revolver shows his obvious interest.