The role of subdeacon was not considered to have been established by Christ nor was it considered a sacrament. It was considered a sacramental established by the Church. Thus the power conferred was of Church law and not divine law. The role they played appears to simply be the inferior roles of a deacon. The Church instituted this divided role of the diaconate for practical reasons
It appears to originally have been considered a minor order but was elevated to a major order around the 12th century. However this was a major order of the Church’s laws and imparted no power of a sacrament.
In the Eastern Churches the subdeacon was conferred through the laying on of hands, but not in the Latin Church. In the Latin Church it was conferred through symbolic rites including the chalice, paten, book of the epistles, and closed with a blessing.
