Many people use the terms consecrated and blessed interchangeably, but there is actually a difference. Blessing is the bestowal of grace upon a person, or in the case of an object, the prayer that the use of the object may allow grace to be bestowed upon the person using it. Consecration is not about an external bestowal of grace, but a solemn dedication of the entirety of the person being consecrated towards God. It is a binding placed upon reality by the Church concerning a certain person. In the case of Holy Orders, the Church uses its authority to change the person on a spiritual level. Their souls are now inherently ordered to a specific duty, that is, service in the ministry of the deaconate, presbyterate, or episcopate.
In Confirmation, people are both blessed and consecrated. They are sealed with the Holy Spirit, that is, the Holy Spirit comes down upon them in the form of grace. Their lives are also consecrated to God in the process of the sealing. When the bishop gives the Confrimand a light slap it is meant to be an awakening to the change in the reality of their lives. It is as if the Bishop is saying, “Wake up! Your life is now God’s. You belong to him.”
God Bless,
Br. Ben, CRM