The antonym for "more rattled" is composed or calm. When someone is calm, they are not shaken, disturbed, or agitated by something or someone. They maintain a sense of inner peace and stability that allows them to handle stressful situations with ease. On the other hand, when someone is rattled, they become nervous, anxious, or upset quite easily. A person who is composed, even in the midst of chaos, is more likely to make clear-headed decisions that will lead to positive outcomes. Therefore, when we strive for calmness in our everyday lives, we are avoiding the risks and negative consequences of being constantly rattled.