This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鉰 combines 金 (metal) with 司, which likely contributes the sound. The exact historical development and original meaning are uncertain.
The left side is metal 金, and the right side is 司 (often associated with administering or controlling). Picture a metal tool used for managing something, but its exact purpose is unknown.
For シ, imagine a sheet of metal being shaped by a tool: sheet -> シ, and the metal 金 is being worked.