What is the origin of the idiom "put the knife into someone" and when to use it?

The origin of the idiom "put the knife into someone" likely stems from the imagery of using a sharp knife as a tool for both constructive and destructive purposes. While knives are often used for productive tasks like cutting and cooking, they can also be used for harmful intentions, such as causing injury or harm. It is typically used in situations of conflict, rivalry, or when someone wants to express strong disapproval or resentment towards another person.