What this suffix does
-willed forms compound adjectives that describe the strength, quality, and moral direction of a person's will — their capacity for determination, resistance, and self-direction. Strong-willed, iron-willed, weak-willed, self-willed, ill-willed — each compound describes not just how much determination someone has but what that determination is like and where it is pointed. These compounds are among the most powerful character descriptors in English because the will is seen as the core of moral agency: how you will something says everything about who you are.