This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鉽 combines 金 (metal) with 式, which likely contributes the sound. The exact historical development is uncertain, and no clear meaning is recorded.
The kanji has no clear meaning, but visually it shows metal 金 beside a form 式. It might be remembered as an obscure metal-related character.
For ショク, imagine a shock of metal: shock -> ショク, and the metal radical 金 reinforces the scene.