Female submission
Wonder Woman's original key weakness was permitting herself to be bound by a man. While this exploitable weakness has since been retconned out of continuity by DC comics, it was absolutely key to the character Dr. Marston, an ardent feminist and practicing psychologist, was creating. His point was that women are not actually inferior to men, they are oppressed. The only reason they are "weaker" is because they allow men to make them so.