• 鋭するどい — sharp; keen
• 鋭利えいり — sharp; pointed
• 精鋭せいえい — the elite; the best and sharpest
• 新鋭しんえい — up-and-coming; new and energetic
• 気鋭きえい — keen and spirited (person)
• 鋭するどさ — sharpness; keenness

鋭 is built from the radical 金 “metal” plus the phonetic element 兑（エイ）. Imagine the edge of a metal blade that cuts cleanly — the sense becomes “sharp, keen, pointed.”