In formal armory, impalement is the method of marshaling two distinct coats of arms on a single escutcheon, achieved by dividing the field vertically (per pale). The Dexter side (the viewer's left) historically contains the arms of the husband, while the Sinister side (the viewer's right) contains those of the wife. This practice serves as a legal and genealogical record of a union between two armigerous houses, visually demonstrating the alliance of bloodlines and the fusion of feudal interests.
Beyond matrimonial unions, impalement is utilized to signify the holding of a high office. In such instances, the arms of the see, cathedral, or office (such as those of an Anglican Bishop or the Garter King of Arms) occupy the Dexter half, while the incumbent's paternal arms occupy the Sinister. This signifies a mystical 'marriage' to the office. Notably, if a wife is a heraldic heiress, her arms are typically displayed on an escutcheon of pretence rather than through impalement, marking a significant distinction in the transmission of feudal titles and lands.