to stain, to dye
擩 centers on applying color to something by soaking or rubbing: staining or dyeing fabric or other materials.
擩 combines 扌 (hand) with 需, which likely contributes the sound and may relate to soaking or softening. The exact historical development is uncertain.
The hand 扌 beside 需 (which suggests need or moisture) gives the image of a hand dipping cloth into dye: staining and dyeing.
For ジュ, imagine a jeweler staining a gem to enhance its color: jew -> ジュ, and the hand carefully applies the dye.