178. After the Universal Prayer, while the Priest remains at the chair, the Deacon prepares the altar, assisted by the acolyte, but it is the Deacon’s place to take care of the sacred vessels himself. He also assists the Priest in receiving the people’s gifts. After this, he hands the Priest the paten with the bread to be consecrated, pours wine and a little water into the chalice, saying quietly, By the mystery of this water, etc., and after this presents the chalice to the Priest. He may also carry out the preparation of the chalice at the credence table. If incense is being used, the Deacon assists the Priest during the incensation of the offerings, the cross, and the altar; and after this the Deacon himself or the acolyte incenses the Priest and the people.
When you have a sacristan/acolyte working with the deacon, the division of duty is clear: clergy get the vessels, lay person gets everything else. Though the option is given to prepare the chalice at the credence table, it seems to be better placed at the altar. If people out there are in parishes that do prepare the chalice and wine at the credence table, what’s the reason behind it for you?
179. During the Eucharistic Prayer, the Deacon stands near the Priest, but slightly behind him, so that when necessary he may assist the Priest with the chalice or the Missal.
From the epiclesis until the Priest shows the chalice, the Deacon usually remains kneeling. If several Deacons are present, one of them may place incense in the thurible for the Consecration and incense the host and the chalice at the elevation.
The kneeling seems presumed throughout the Eucharistic Prayer. The emphasis on kneeling from the epiclesis to the mystery of faith seems to address the (real or imagined) problem of the deacon seeming like a con-celebrant.
180. At the concluding doxology of the Eucharistic Prayer, the Deacon stands next to the Priest, and holds the chalice elevated while the Priest elevates the paten with the host, until the people have acclaimed, Amen.
So the deacon stands, and moves forward at the doxology.
181. After the Priest has said the prayer for the Rite of Peace and the greeting The peace of the Lord be with you always and the people have replied, And with your spirit, the Deacon, if appropriate, says the invitation to the Sign of Peace. With hands joined, he faces the people and says, Let us offer each other the sign of peace. Then he himself receives the Sign of Peace from the Priest and may offer it to those other ministers who are nearest to him.
Invitation to peace still optional.
182. After the Priest’s Communion, the Deacon receives Communion under both kinds from the Priest himself and then assists the Priest in distributing Communion to the people. If Communion is given under both kinds, the Deacon himself administers the chalice to the communicants; and, when the distribution is over, standing at the altar, he immediately and reverently consumes all of the Blood of Christ that remains, assisted, if the case requires, by other Deacons and Priests.
183. When the distribution of Communion is over, the Deacon returns to the altar with the Priest, collects the fragments, should any remain, and then carries the chalice and other sacred vessels to the credence table, where he purifies them and arranges them as usual, while the Priest returns to the chair. Nevertheless, it is also permitted to leave vessels needing to be purified on a corporal, suitably covered, on the credence table, and to purify them immediately after Mass, following the Dismissal of the people.