This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
嫆 combines 女 (woman) with 容, which likely contributes the sound. The exact historical development is uncertain.
A woman 女 beside 容, a shape associated with appearance or form. Without a clear meaning, picture a woman whose form is graceful but whose name is forgotten.
For ヨウ, imagine a woman named Yoko standing beside a container 容: Yoko -> ヨウ, and her name is the only clue to this rare kanji.