Wow. I am curious, what is the German term for that? That phrase sounds so wrong that I am wonder whether it maybe simply does not translate all that well into English. Weapons are for offense not defense!
The phrase is a literal translation. I suspect they choose this wording to misslead, to be able to implement the law.
Just like they passed a new law in recent times, that increased the punishments, when firefighters and medics etc. gets attacked during work. Sounds good as well, I mean, what asshole would attack medics and firefighters?!?
The thing is just, that the law also applied to policemen. So when you are in a demonstration, peaceful and are about to get hit by the police who decided to end the demonstration with force, and your reflexes push back - then you can get prosecuted with a law that was advertised to protect firefighters.
This includes the thing boxers put in their mouth to protect their teeth... let that sink in. Carrying something like that to a protest already is a crime, maximum sentence is 1 year.