This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
銊 combines the metal radical 金 with 戍, but the exact historical development and original meaning are uncertain.
The metal radical 金 suggests something metallic, and 戍 looks like a guard or weapon. Picture a metal tool or weapon, but its exact use is unclear.
For シュツ, imagine a metal tool making a sharp 'shoot' sound as it cuts: shoot -> シュツ, tying the metallic shape to the reading.