This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 躮 is uncertain. It visually combines 身 (body) and 分 (part/divide), but this may be a modern or obscure formation without a well-documented origin.
The kanji has 身 (body) and 分 (part). Imagine a body part being divided or separated, but since the meaning is unclear, treat this as a visual hint only.
For サガレ, picture a sagging body part that falls (sagare) when divided: sag -> サガ, and the body part sags lower. The invented hook 'sagare' cues サガレ.