Acts 10:38 “I take it you know what has been reported all over Judea about Jesus of Nazareth, beginning in Galilee with the baptism John Preached, of the way God anointed him with the Holy Spirit and power. He went about doing good and healing.”
The sacrament of confirmation presupposes the mark of baptism, and cannot be given without it. The character of Confirmation, of necessity supposes the baptismal character: so that, in effect, if one who is not baptized were to be confirmed, he would receive nothing, but would have to be confirmed again after receiving Baptism. (ST III, 72)
Confirmation makes us soldiers of God. It has been variously designated a making fast or sure, a perfecting or completing, as it expresses its relation to baptism.It is, after baptism, the next Sacrament of Initiation. But what does it do? Again, we listen to St. Thomas:
“Now it has been said above (1; 65, 1) that, just as Baptism is a spiritual regeneration unto Christian life, so also is Confirmation a certain spiritual growth bringing man to perfect spiritual age. But it is evident, from a comparison with the life of the body, that the action which is proper to man immediately after birth, is different from the action which is proper to him when he has come to perfect age. And therefore by the sacrament of Confirmation man is given a spiritual power in respect of sacred actions other than those in respect of which he receives power in Baptism. For in Baptism he receives power to do those things which pertain to his own salvation, forasmuch as he lives to himself: whereas in Confirmation he receives power to do those things which pertain to the spiritual combat with the enemies of the Faith.” (Summa III, Q.72)
“There has been much discussion among theologians as to what constitutes the essential matter of this sacrament. Some, e.g. Aureolus and Petavius, held that it consists in the imposition of hands. Others, with St. Thomas, Bellarmine, and Maldonatus, maintain that it is the anointing with chrism.” (NewAdvent.org) However, both are always present when the sacrament is given. Only the bishop may consecrate the oil, and it is preferred that it always be the bishop that administers the sacrament itself, because it symbolizes communion with fullness of apostolic ministry and origins of the Church.
St. Thomas, quoting the letter of an early pope in the Summa Theologica, puts it as straight forward as possible:
Pope Eusebius says: “The sacrament of the imposition of the hand should be held in great veneration, and can be given by none but the high priests. Nor is it related or known to have been conferred in apostolic times by others than the apostles themselves; nor can it ever be either licitly or validly performed by others than those who stand in their place. And if anyone presume to do otherwise, it must be considered null and void; nor will such a thing ever be counted among the sacraments of the Church.” Therefore it is essential to this sacrament, which is called “the sacrament of the imposition of the hand,” that it be given by a bishop.(Summa III, Q.72)
Besides sanctifying grace, the sacrament also confers the seven gifts of the Holy Spirit. These are, according to Scripture and the Catechism of the Catholic Church, wisdom, understanding, counsel, fortitude, knowledge, piety, and fear of the Lord. They belong in their fullness to Christ, Son of David. They complete and perfect the virtues of those who receive them. They make the faithful docile in readily obeying divine inspirations.(CCC 1831)