A woman is shown as weak, incompetent, and ineffectual in this trope unless she dresses and behaves in a masculine manner. A common variation on this is to present a woman as superior because she’s “not like other women.” Another variation is a Tomboy and Girly Girl scenario, where the tomboy is presented as superior. We’re just recording the trope, here. It happens. Between a woman in trousers and one in a dress, the odds are the trouser lady is going to be the Action Girl of the pair and the one in the dress is going to be a Damsel in Distress.
Variations exist, of course, especially in works after the third-wave “Girl Power” feminism. Many of the straight examples are from older works, when having proactive female characters at all was fairly edgy. See also Pink Means Feminine and the various tropes on Acceptable Feminine Goals And Traits. Contrast Girly Bruiser, Lady of War and Kicking Ass in All Her Finery, where it’s the feminine lady in the dress who you should watch out for. Also, compare Vasquez Always Dies, where trouser-wearing and competence aren’t enough to keep a woman alive, and Real Men Wear Pink.
Note: This is not an audience reaction trope. The trope is reserved for cases where a character is derided by another character in-universe for having traditionally feminine traits, or where the work itself clearly portrays femininity as a sign of weakness or inferiority.