Wives of shoguns and warriors (women in the samurai class) were always armed (with a dagger), and were trained from childhood to defend themselves, both with the dagger and with the naginata, which was a sword mounted on a pole. So you did not mess around with them.
Understood, but HUSBAND still had the right to beat the holy crap out of them. So, though warrior/shogun husbands COULD have beaten up wives, since it was/is so much of the culture, they DIDN'T. Are you telling me that wives would fight back? I don't think they would...and they wouldn't stand much of a chance again their husband.
Side note: MY husband always told me that there is NO defense for some pissed off person to sneak up on someone they hated and BASH the guy in the head with a two-by-four...with nails :o).