Alphonso, or Alonzo.  From the Teutonic, meaning "battle eager."  Danish, Alfons; Fr., Alphonse; It., Alfonso; Lat., Alphonsus; Port., Affonso; Sp., Alfonso, or Alonso. (The Standard Dictionary of Facts, Ruoff, 1922)

ALPHONSO.  This name is usually derived from the Gothic helpuns (say hialp-uns), our help; but to arrive at the origin of the name we must compare it with the Spanish names Ildefónso, Alfónso, Alónso, which all represent Alphonso.  Now, the second has been abbreviated from the first, and the third from the second.  The name Ildefónso is derived from the Old German saint-name Hildefons, or, as some write it, Hildefuns.  The latter has been rendered "battle-eager." (Praenomina, Charnock, 1882) 

Alphonso, King of Spain, is the thirteenth of his historic and time-honoured name in that country.  The first was Alphonso the Catholic, King of the Asturias, 739-58.  The tenth was Alphonso the Wise, the competitor of Richard, Earl of Cornwall, for the Imperial crown.  It was his sister Eleanor who was the beloved wife of Edward I.  Their third son Alphonso, born at Beaune, in Gascony (famous for its wine), on the morrow of St. Clement, 1274, became by the death of his brothers, his father's heir, but died when ten years old, 19 Aug., 1284, and was buried in Westminster Abbey. (Notes and Queries, White, v.114, 1906)