There was an incident a few years back where a wife fatally stabbed her husband with a sword. In fact, she had bullied her husband for years, often threatening him with the blade. One day, she made good on the threat and actually ran him through. No gun involved, but still just as lethal.
Point is, you cannot pass any amount of legislation that will stop domestic violence as it is occuring. Due to the nature of domestic violence, taking place in private makes it unlikely anyone outside of that home is going to notify authorities until *after* the violence has already occurred.
Resources are better spent educating kids on how to handle disputes, so when they grow up, they become stable, functional adults who can resolve conflicts properly. Or at the very least, if an agreement cannot be made, to at least have the self control to walk away from it. It'd also help if people were wiser about who they got involved with, romantically.
Of course, if things do become violent, a weapon is actually an equalizer for the physically weaker spouse. Given the facts of human biology, that most often is the woman.