This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鞢 is a rare character combining 革 (leather) with 枼, which likely contributes a phonetic element. The exact historical development is uncertain.
With no clear meaning, picture a mysterious leather object marked with the shape 枼—perhaps an old tag or label whose purpose is now forgotten.
For ショウ, imagine showing (ショウ) someone this strange leather item and asking what it is. The sound 'show' cues ショウ.
—