Or HaChaim on Genesis 32:31/אור החיים על בראשית ל״ב:ל״א

1 פנים אל פנים, face to face. Jacob's amazement was not due to the fact that he had had an encounter with an angel; he had previously encountered angels. What amazed him was that he had been in a confrontation with an angel. The word פנים אל פנים is a term used in warfare as we know from Kings II 14,8.