Trenchant

trenchant \ˈtrent-chənt\ adjective: 1. keen; sharp, 2. vigorously effective and articulate {a trenchant analysis}; caustic {trenchant remarks}, 3 a. sharply perceptive; penetrating {a trenchant view of current conditions}, b. clear-cut; distinct {the trenchant divisions between right and wrong — Edith Wharton}

Etymology: Middle English trenchaunt, from Anglo-French

A lot of usage examples for you with this one.