silver plating
鋈 centers on the process of coating a metal surface with silver: silver plating. The meaning is specific and technical, without broader abstract extensions.
鋈 combines 金 (metal) with 沃, which likely contributes the sound. The character is a specialized phono-semantic compound for silver plating.
The bottom 金 is metal, and the top 沃 looks like a liquid being poured. Imagine molten silver flowing over a metal surface to plate it.
For ヨク, picture a silversmith carefully plating a metal piece and saying 'yoku dekimashita' (well done) when the silver coating is perfect: yoku -> ヨク.