We read in the General Introduction “If necessary, the sacrament also provides the sick person with the forgiveness of sins and the completion of Christian penance.”(6) This line in the General Introduction reflects St Thomas understanding of the sacrament.
“Let him call for the presbyters of the Church”
We read in the Catechism of the Catholic Church “Only priest (bishops and presbyters) are ministers of the Anointing of the Sick. The faithful should encourage the sick to call for a priest to receive this sacrament. The sick should prepare themselves to receive it with good dispositions, assisted by their pastor and the whole ecclesial community, which is invited to surround the sick person in a special way through prayers and fraternal attention.”(1516) If circumstances suggest it, the celebration of the sacrament can be preceded by the sacrament of Penance and followed by the Eucharist. As the sacrament of Christ’s Passover the Eucharist should always be the last sacrament of the earthly journey, the ‘viaticum’ for ‘passing over’ to eternal life.”(1517) Properly speaking the Church view Eucharist as victicum as the sacrament of the dying and not Anointing of the Sick or by another name Last Rites.
While the Sacrament of Anointing of the Sick is not primarily oriented towards forgiveness of sins it is connected to the sacrament of Penance. We read in the General Introduction “If necessary, the sacrament also provides the sick person with the forgiveness of sins and the completion of Christian penance.”(6) St Thomas would say Penance forgives sins. The Sacrament of Anointing of the Sick heals the effects of sin. This organically connects the two sacraments together. This organic connect between the two sacrament might be a reason why as the catechism says “”Only priest (bishops and presbyters) are ministers of the Anointing of the Sick.”
Another connection between the Sacrament of Anointing and priesthood. When the priest anoints he is acting ‘In the person of Christ the head.” As the Catechism says “In the ecclesial service of the ordained minister, it is Christ himself who is present to his Church as Head of his body, Shepherd of his flock, high priest of the redemptive sacrifice, Teacher of Truth. This is what the Church means by saying that the priest, by virtue of the sacrament of Holy Orders, acts in persona Christi Capitis.”(CCC 1548)
When a priest gives the sacrament of Anointing of the Sick. The person is receiving a blessing from the priest acting in the person of Christ the Head.