By definition, a melodrama features very exaggerated mannerisms on the part of the characters involved. Audiences at melodramas are frquently encouraged and expected to identify with the heroines as they endure trials and tribulations through the course of the play.
As a result, expressions of a damsel in distress should be as large and dramatic as possible. Upon seeing something that is somewhat distasteful, the damsel would shrink back away from the object, shielding her eyes from any further sight of the item, screaming her disgust while holding her handkerchief to her hose.
If the damsel is in danger, she should be doing everything possible to escape. Kicking, beating her captor with her umbrella or purse or hands, shrieking loudly, pleading for any passers-by to come to her rescue - all would be very in character. If she's already been tied up and left on the train tracks in front of the approaching train, she should at least continue to use huge facial expressions along with her voice to convey her helplessness and dismay. Victorian damsels were very capable of making themselves heard in any and all situations!