Valiant, a.
Etymology: [OE. valiant, F. vaillant, OF. vaillant, valant, originally p. pr. of OF. & F. valoir to be worth, L. valere to be strong. See Wield, and cf. Avail, Convalesce, Equivalent, Prevail, Valid.]
1. Vigorous in body; strong; powerful; as, a valiant fencer. [Obs.] Walton.
2. Intrepid in danger; courageous; brave. A valiant and most expert gentleman. Shak. And Saul said to David . . . be thou valiant for me, and fight the Lord's battles. 1 Sam. xviii. 17.
3. Performed with valor or bravery; heroic. "Thou bearest the highest name for valiant acts." Milton. [The saints] have made such valiant confessions. J. H. Newman. -- Val"iant*ly, adv. -- Val"iant*ness, n.
Shades of meaning
Fernald has no entry of its own for valiant; he lists it under brave.
Where he writes about it:
Courageous is more than brave, adding a moral element: the courageous man steadily encounters perils to which he may be keenly sensitive, at the call of duty; the gallant are brave in a dashing, showy, and splendid way; the valiant not only dare great dangers, but achieve great results; the heroic are nobly daring and dauntless, truly chivalrous, sublimely courageous. — from brave