>>96131442
GURPS: Martial Arts gives you all you need to run sword fights, including multiple different styles (kenjutsu, iajutsu, etc) with their own techniques as well as universal techniques and maneuvers to make sure "I swing my sword" is never the only thing you can do.

As for guns being lethal, a TL 5 (Bakumatsu era) rifle deals 5d6 pi+ damage - enough to kill an average warrior (10-13 HP) in one good shot, and easily piercing contemporary samurai armor.

>>96032790
>Eons ago, GURPS was on my mind
Your instincts were correct. Come home, Aryan man.