The phrase more weak-kneed implies a lack of bravery or fortitude. The antonyms for weak-kneed would be words that describe courage, strength, and fearlessness. Some of these antonyms include brave, bold, fearless, courageous, confident, resilient, resolute, and stoic. Opposite meanings can be found in these words as they suggest one's ability to overcome fear or intimidation. These traits require a strong will and mental or physical toughness to make hard decisions, continue on in the face of adversity, and stand up for what is right. These antonyms emphasize strength over weakness and inspire action over hesitation.