There are many synonyms for the phrase "weapon of terror," which refers to a tool used to instill fear and intimidate others. Some common synonyms include "instrument of fear," "tool of horror," and "device of terror." Other variations include "weapon of mass destruction," which is often used to describe nuclear or chemical weapons, and "terrorist weapon," which specifically refers to tools used in acts of terror. Regardless of the specific term used, these synonyms all convey the same idea: that the weapon being described is intended to cause harm and instill fear in others.