This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鑜 combines 金 (metal) with 賞, which likely contributes the sound. The exact historical development is uncertain.
The metal radical 金 suggests something metallic, but the overall meaning is unclear. Imagine a mysterious metal object with an unknown purpose.
For ショウ, picture a show of rare metal artifacts: show -> ショウ, and this kanji is one of the mysterious pieces on display.