In self-defense, how can the victim kill the offender with a knife or a knife? How to sentence passers-by who cut or mend knives to criminals?

It depends on what kind of crime the suspect committed.

For ongoing violent crimes such as assault, murder, robbery, rape and kidnapping that seriously endanger personal safety, due to the serious nature, intensity and urgency of these illegal acts, taking justifiable defense and causing casualties and other consequences does not belong to excessive defense and does not bear criminal responsibility. The so-called "other violent crimes that seriously endanger personal safety" refers to violent crimes similar to assault, murder, robbery, rape and kidnapping, such as explosion crimes committed in a crowd.

If it does not belong to the above violent crimes, it may be suspected of excessive defense. The crime of excessive defense mainly includes (indirect) intentional homicide, negligent death, (indirect) intentional injury and negligent serious injury. Paragraph 2 of Article 20 of the Criminal Law stipulates that excessive defense: "Punishment shall be mitigated or exempted".