help
裨 centers on providing assistance or support, with the core idea of helping or supplementing something.
裨 combines 衤 (clothing) with 卑, which likely contributes the sound and possibly the idea of something supplementary or attached, as clothing supplements the body.
The clothing radical 衤 suggests something worn close to the body, and 卑 can be seen as a servant or helper. Together, 裨 is like a garment that helps or supports the wearer.
For ヒ, imagine a helper handing you a warm 'he'ating pad: 'he' -> ヒ, and the help warms you like clothing.