This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鍒 combines the metal radical 金 with 柔, which likely contributes a phonetic element. The exact historical development is uncertain.
The metal radical 金 suggests something related to metal, but the overall meaning is obscure. Imagine a soft, flexible metal that is gentle like 柔.
For ジョウ, imagine a soft metal Joe bending easily: Joe -> ジョウ, and the metal is as pliable as Joe's gentle touch.