Im guessing its because unlike today we have weapons that does not need us to move our body that much like guns, tasers even tanks but previously all they had are swords that requires them to train their body to be able to move them as they will also they also have machines such as catapults but still requires 100% human involvement to operate. Im also guessing that the gun they have in this series is still new in their era ┑(￣Д ￣)┍ this is just what I think (●'◡'●)ﾉ
Right like even bow and arrows used to require an insane amount of arm and shoulder strength to use
Just wondering how are they so rip in these era. Like every historical manga they have muscles and shi