cloth covering
幎 centers on a cloth that covers or veils something, like a shroud or curtain. The given meaning 'cloth covering' captures this idea of a fabric layer used to conceal or wrap.
幎 combines 巾 (cloth) with 冥, which likely contributes both sound and the idea of darkness or concealment, suggesting a cloth that covers or veils.
The left side 巾 is a cloth, and the right side 冥 suggests darkness or obscurity. Picture a dark cloth draped over an object, completely covering it from view.
For ベキ, imagine a cloth covering a beckoning hand: beck -> ベキ, and the cloth veils the mysterious gesture.