luster, glaze, polish, charm, colorful, captivating
艷 centers on a rich, attractive surface quality: luster, glaze, or polish that makes something colorful and captivating. The charm sense is the natural effect of that glossy, eye-catching appearance.
艷 combines 豐 (abundant, lush) with 色 (color, appearance), suggesting a rich, glossy surface or captivating beauty. The exact historical development is uncertain, but the component combination fits the meaning well.
On the left, 豐 suggests abundance and richness; on the right, 色 is color. Imagine a surface so richly colored and polished that it gleams with luster and charm.
For エン, picture an enchanting glaze that makes you say 'en!' in admiration: en -> エン, and the glossy surface captivates you.
charming; bewitching; coquettish