Coat of Arms of Luis de Borbón, infante of Spain, without ecclesiastical ornaments (before he abandoned the ecclesiastical life).
Infante Luis used a plain label as difference in his Coat of arms as Cardinal and Archbishop of Toledo, without a crown. He changed this difference for the open crown (later named Crown of Infantes) in his arms without ecclesiastical ornaments.  See the source below.  The Spanish House of Bourbon had no formal rules for cadency at that time. Royal Family member's arms were created ad-hoc.  The Heir Apparent of Spain frequently used the undifferentiated royal arms, with the title's crown.  

Source:   Menéndez Pidal y Navascués, Faustino, Hugo. El escudo. P. 248. At Menéndez Pidal y Navascués, Faustino; O´Donnell y Duque de Estrada, Hugo; Lolo, Begoña. Símbolos de España. Madrid: Centro de Estudios Políticos y Constitucionales, 1999. ISBN 84-259-1074-9
Own work
Proof02