Refers to refined manual skill or craftsmanship, often implying practiced, impressive ability.
I'm always amazed by his dexterity.
It's a work that showcases the craftsman's skill.
Compound of 腕 (ude, 'arm; skill') + の (no, possessive particle) + 冴え (sae, 'clearness; sharpness'), literally 'sharpness of skill'.