E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Cut a Dash.
Make a show. Cut is the French couper, better seen in the noun coup, as a grand cou&pgrave;, a coup de maître (a masterly stroke), so to cut means to make a masterly coup, to do something to be looked at and talked about. Dashing means strikingi.e. showy, as a dashing fellow, a dashing equipage. To cut a dash is to get ones self looked at and talked about for a showy or striking appearance.