exceedingly feminine, lady attendant, maid
妼 centers on a woman in a serving role: a lady attendant or maid, with a nuance of being exceedingly feminine or refined.
妼 combines 女 (woman) with 必, which likely contributes a phonetic element. The exact historical development is uncertain, but the character is associated with feminine service roles.
A woman 女 who is necessarily 必 present to attend to a lady: a maid who embodies refined femininity.
For ヒ, imagine the maid saying 'Hee!' in a high, feminine voice as she attends to her lady: 'Hee' -> ヒ.