belt
纕 centers on a belt, specifically a sash or cord worn around the waist.
纕 combines 糸 (thread) with 襄, which likely contributes the sound. The thread component suggests a woven belt or sash.
The left side 糸 is thread, and the right side 襄 looks like a wrapped bundle. Picture thread woven into a long belt wrapped around the waist.
For ショウ, imagine a showy belt made of silk thread: show -> ショウ, and the belt is the star of the outfit.