This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
銉 is a rare character combining 金 (metal) and 聿. The exact historical development is uncertain.
The kanji has 金 (metal) on the left and 聿 (a brush or writing instrument) on the right. Without a clear meaning, picture a metal stylus or needle used for writing or piercing.
For イツ, imagine an itsy-bitsy metal needle (金) writing tiny characters with a brush (聿): itsy -> イツ.