Fun fact Japan kept trying to conquer Korea specifically to get their Iron deposits. Japanese Iron is pretty shit comparable to Iron used for nails, which is also why Japanese steel was created it was to compensate for shitty iron.

Also as you noted Japanese sword focused martial arts is notably different from everyone else in its focus to avoid certain strikes so as to not destroy or ruin the blade. Meanwhile in Europe, the middle east, and China for example there were multiple forms of sword martial arts focused on specifically cleaving through bone.