Why do Japanese samurai hold knives with both hands, while China samurai use one hand?

That's not to say. Japanese samurai hold knives with both hands because Japanese knives are designed to highlight the performance of holding knives with both hands, so most of them hold knives with both hands, but there are also masters with one hand.

They're not called samurai in China. The use of weapons really depends on factions and characteristics, and cannot be generalized. There is one hand and two hands.