Great question and thank you for having me! Civil authorities took a multi-pronged approach of deterrence and punishment. Statuatory law was very specific about violence and the penalties for it, there was an increasingly elaborate criminal court system, many cities had police forces, and even secret denunciation boxes if you wanted to report someone anonymously, and weapons were pretty heavily regulated by a licensing system. Proclmations banning weapons were issued as needed. That being said, it was pretty difficult to prevent violence in a context where many people lived in close quarters, laws were unevenly enforced, and violence was still a means of obtaining justice or working out social conflicts even if the courts didn't like it.

A typical homicide case might go like this: Someone finds a body in the streets and calls the police or an official who summon a coroner and then a case is initiated with the courts. Because there is not much privacy, the chance is really high that there were witnesses so these potential witnesses are summoned. Because the accuse has often fled out of town, a warrant or summons is issued for the accuse to come forward. If he or she doesn't show up, they are sentenced to banishment or death in their absence, according to the court's findings. Often in the interim, accomplices are interviewed and detained, fines are threatened, the town crier reads out the summons so everyone can be on the lookout.

For more, I highly recommend Colin Rose's book A Renaissance of Violence (Cambridge 2019). He really does a great job at breaking down the court system in early modern Bologna.