Or a Deacon, without his vestments (maybe he came to Mass as a parishioner, and then was called upon to assist with the distribution?)
QUOTE]
A cleric should never distribute communion without a stole.
Though I just can’t see the reason for having an extra minister for communion at all in this case, why have communion under both kinds, it is perfectly good to receive under one alone. Indeed it reamins the norm of the Universal Church to receive under under the Species of bread alone, and in most places where it is permitted to receive under both species it is technically only to be done on feasts and special events such as Ordinations etc. I do see that if it was a Sunday Mass and there was a Cleric (Ordinary Minister of Holy Communion) either concelebrating or sat in choir then it may be practical and may even be said by some to be suitible to distribute both species, preferably by intiction.
As it is late here I will restrict myself to finishing by quoting from The Roman Catechism.
**"Why The Celebrant Alone Receives Under Both Species **
It is clear that the Church was influenced by numerous and most cogent reasons, not only to approve, but also to confirm by authority of its decree, the general practice of communicating under one species. In the first place, the greatest caution was necessary to avoid spilling the blood of the Lord on the ground, a thing that seemed not easily to be avoided, if the chalice were administered in a large assemblage of the people.
In the next place, whereas the Holy Eucharist ought to be in readiness for the sick, it was very much to be apprehended, were the species of wine to remain long unconsumed, that it might turn acid.
Besides, there are many who cannot at all bear the taste or even the smell of wine. Lest, therefore, what is intended for the spiritual health should prove hurtful to the health of the body, it has been most prudently provided by the Church that it should be administered to the people under the species of bread only.
We may also further observe that in many countries wine is extremely scarce; nor can it, moreover, be brought from elsewhere without incurring very heavy expenses and encountering very tedious and difficult journeys.
Finally, a most important reason was the necessity of opposing the heresy of those who denied that Christ, whole and entire, is contained under either species, and asserted that the body is contained under the species of bread without the blood, and the blood under the species of wine without the body. In order, therefore, to place more clearly before the eyes of all the truth of the Catholic faith, Communion under one kind, that is, under the species of bread, was most wisely introduced.
There are also other reasons, collected by those who have treated on this subject, and which, if it shall appear necessary, can be brought forward by pastors."