The proper synonym for BRAVERY is COURAGE. This is because it embodies the mental/moral fortitude to undertake risks, persevere, and confront danger, fear, and adversity.
Courage: The ability to do something that frightens one; bravery.
Lithe: Thin, supple, and graceful (unrelated).
Bellicose: Demonstrating aggression and willingness to fight (different nuance).
Timid: Showing a lack of courage or confidence; an antonym of bravery.