On balance, I'd say good, and that's after silencing my inner feminist's victory cheer.

Given that rapes in this setting have frequently involved beatings up to and including murder, it's hardly going to make the level of violence worse. This kind of rape is basically bullying - with all that that implies in the bullies being victims themselves, who deal with their abuse by passing it on to someone weaker - and it's widely held that the only thing that will stop a bully is the threat of force.

It's not a long term solution, in the same way that more guns are not the solution to gun crime. And carrying a knife does not automatically make you safer: as any combat expert will tell you, and as kids in the hood learn every day, a knife you can't use is a weapon for your opponent. But as a short term fix for a very sick situation, it will help. Even if nobody else carries a knife, if a few would-be rapists think twice because she might, there will be a few less rapes as a result.

Ideally, I'd say she should be arrested and tried, even though it sounds like an open and shut case of self defence, just to make it clear that this is within the rule of law. (When someone shoots a burglar or knocks out a mugger, the tabloids are always up in arms when they're arrested and charged: but the whole point is to clear their name legally.) From the sound of it, I'm guessing that one reason the police are making such a heroine of her is that it gives them an excuse to save the community the embarrassment of such a trial.