The antonyms for the word "weak-kneed" are strong, resolute, and decisive. A person who is strong-willed and determined is unlikely to have weak knees. They may be brave or courageous in the face of danger or adversity. On the other hand, someone who is weak-kneed might be timid or cowardly. Decisive individuals are not weakened by uncertainty and can make quick and confident decisions. They are often seen as confident and assertive. In contrast, weak-kneed individuals may waver or hesitate, lacking the confidence to take action. It is clear that antonyms for weak-kneed are mostly related to confidence and strength of character.