I've spent too long on Reddit today so I'll be very brief:

You have to get out of thinking of Athenian Democracy as we think of Democracy. It wasn't that great for all (slaves, treatment of women, stupid leadership, incredibly unstable, coups). Which leads to (and may be a result of) the second point- very few contemporary writers who analyzed the democracy liked it that much (Plato, the old oligarch, Thucydides and to a lesser extent Aritophanes).

It could be extremely brutal i.e trial of Socrates and the actions of the Delian League such as the massacre of the Melians. They also had murders. Just look at the law court speeches. Probably the best know is Lysias 1: On the Murder of Eratosthenes, but there are quite a few others.

But to answer your question - Athens was not immune to violence, and the way democracy was described makes it sound even more violent. But in a direct comparison to another context I'm not too sure. How do you even quantify things like violence without anything approaching quantitative data like official crime statistics?

This is massively too brief and over simplistic and I can make a better job of it latter on.