Blessings & Extraordinary Ministers of Holy Communion

Canon 1169
1. Persons who possess the episcopal character as well as presbyters to whom it is permitted by law or by legitimate concession can validly perform consecrations and dedications.
2. Any presbyter can impart blessings, except those which are reserved to the Roman Pontiff or to bishops.
3. A deacon can impart only those blessings which are expressly permitted to him by law.

A blessing is a good conferred by a higher personage on a lower personage. All true blessings ultimately come from God, though they come through those whom He has placed over others. In the family parents bless their children, as God has given them natural authority over their children. In the Church spiritual blessings are conferred in God's Name by those to whom He has given spiritual authority over His People. As is evident by the above, blessings are given by priests (who have the power of the keys), though some are reserved to bishops (high priests). Deacons may also bless, but only where the ritual books, and thus the Church, provide the authority by law. Since the laity do not possess spiritual authority in the Church they cannot confer blessings. The laity can impose some sacramentals (ashes, St. Blaise blessing), but using objects previously blessed by the ordained.

So, the blessing of individuals by an Extraordinary Minister of Holy Communion is a vain gesture, as a ly minister has no authority to bless. Furthermore, by a gesture which suggests priestly authority in a sacramental setting, it confuses the role of the laity and the ordained minister, something explicitly prohibited by the Instruction on Certain Questions Regarding the Collaboration of the Non-Ordained Faithful in the Sacred Ministry of Priests.