Prowess

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Middle English (in prowess (sense 2)): from Old French proesce, from prou ‘valiant’. Sense 1 dates from the early 20th century.

wiktionary

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From Middle English prowesse, prouwesse, proues, prouesce, prouesse(“bravery in battle; act of bravery; excellence; nobility of character; intelligence”), from Old French proeche, proesce, proeësche(“goodness; excellence; bravery”), [1] from Old French preu, prou, prouz, proz, pruz(“good; excellent; brave”). CompareEnglish proud.

etymonline

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prowess (n.)

early 13c., prouesse, "an act of bravery;" c. 1300, "military bravery combined with skill in combat," from Old French proece "prowess, courage, brave deed" (Modern French prouesse), from prou, later variant of prud "brave, valiant," from Vulgar Latin *prodem (source also of Spanish proeza, Italian prodezza; see proud (adj.)). Prow was in Middle English as a noun meaning "advantage, profit," also as a related adjective ("valiant, brave"), but it has become obsolete. "In 15-17th c. often a monosyllable" [OED].