Left-side metal radical, the simplified five-stroke form of
金. The indexing radical —
锐 is sharpness, the keen cutting edge of a metal blade. Family of metal/weapon characters:
剑 sword,
刃 blade,
钢 steel,
银 silver,
钉 nail. Modern senses extend to 'acute, perceptive' (
敏锐), keeping the blade-edge metaphor.