scorn, despise, be rude, affront
嫚 centers on treating someone with contempt: scorning, despising, being rude, or affronting them. The core idea is active disrespect or insult.
嫚 combines 女 (woman) with 曼, which likely contributes the sound and may carry a sense of extended or excessive behavior, together suggesting a woman showing scorn or rudeness. The exact historical development is uncertain.
A woman (女) with a long, drawn-out (曼) attitude of disrespect: she scorns and despises others.
For バン, imagine a woman scorning someone by banning them from her presence: ban -> バン, and her rude affront is the ban.