To be the champion of God’s people, the Jews in the Old Law, the Christians in the New Testament; therefore he was the patron of the Church, and of the orders of knights during the Middle Ages.
To call away from earth and bring men’s souls to judgment (“signifer S. Michael repraesentet eas in lucam sanctam”, Offert. Miss Defunct. “Constituit eum principem super animas suscipiendas”, Antiph. off. Cf. “Hermas”, Pastor, I, 3, Simil. VIII, 3).
Regarding his rank in the celestial hierarchy opinions vary; St. Basil (Hom. de angelis) and other Greek Fathers, also Salmeron, Bellarmine, etc., place St. Michael over all the angels; they say he is called “archangel” because he is the prince of the other angels; others (cf. P. Bonaventura, op. cit.) believe that he is the prince of the seraphim, the first of the nine angelic orders. But, according to St. Thomas (Summa Ia.113.3) he is the prince of the last and lowest choir, the angels. The Roman Liturgy seems to follow the Greek Fathers; it calls him “Princeps militiae coelestis quem honorificant angelorum cives”. The hymn of the Mozarabic Breviary places St. Michael even above the Twenty-four Elders. The Greek Liturgy styles him Archistrategos, “highest general” (cf. Menaea, 8 Nov. and 6 Sept.).