Fr. Matthew concludes this five month reflection on the liturgy of the Echarist from the BAS discussing the blessing and dismissal.
He notes that the blessing is optional and is included from a time where it was common for the people not to receive communion, but is somewhat superfluous for the the blessing of grace in the Body and Blood of Christ received moments before cannot be added to by a simple blessing. Instead we might think of it as a pastoral offering to anyone who does not receive the Eucharist, for whatever reason.
The blessing also carries with it the language of sending forth which is most firmly expressed in the concluding dialogue pronounced by the deacon to go out into the world, strengthened by the proclamation of the word and preaching of the gospel, and by the reception of the sacrament itself, to do the will of God in the world until the body of Christ gathers again to celebrate the glory of God.