A person who uses duress; someone who forces another person to do something through threats or coercion.
From duress with the agent suffix -or, following the pattern of other legal terms like 'aggressor' and 'oppressor' that describe people who commit harmful actions.
This is a rare legal term—you're more likely to hear 'coercer' in modern English—but it perfectly captures the role of someone weaponizing fear to control others' actions.
Complete word intelligence in one call. Free tier — 50 lookups/day.