Which term refers to making something less harsh, violent, or severe?

The term that best refers to making something less harsh, violent, or severe is "assuage." This word specifically implies a soothing or calming effect, often used in contexts where there is a need to reduce intensity or severity, such as alleviating fear, pain, or concern.

In contrast, while "alleviate" can also mean to relieve or make something less severe, it typically focuses more on the reduction of pain or hardship rather than the overall harshness of a situation. "Amend" refers more to making changes or improvements, which does not necessarily imply reducing severity. "Aggravate" has the opposite meaning, as it means to make a problem worse or to intensify a situation.

Thus, "assuage" is the most fitting term for describing the act of making something less harsh or severe.