A melder is a silver weapon that is the elvin equivalent of a gun. From a distance, this weapon will merely stun the person who was shot, although at close range it can cause permanent physical and / or even mental damage. These weapons were first mentioned in Keeper of the Lost Cities, in which the Neverseen threaten to shoot Dex at the kidnapping scene. They were later mentioned in Exile (in which Keefe and Fitz use one), and in Everblaze, where Sophie and Gethen are shot by them. Lady Gisela also used one to threaten Biana.
Biana's dad, Alden, taught her how to pull someone out of the daze that a melder causes. When Sophie was shot, she used the method to help Sophie. To do that, she placed two fingers under her temples. It is described as being very painful.