I think this thread has gone far afield but I hope it’s ok to continue. This is very interesting. Thank you for explaining this so clearly.
If I understand you correctly, the eastern priest acting as the bishop’s delegate in the DL would parallel the western priest acting as the bishop’s delegate in Confirmation. The bishop is the ordinary minister of Confirmation but sometimes he delegates this to a pastor. This isn’t something a pastor can do just by his ordination as a priest. The western idea is that the bishop ordains the priest as ‘a priest forever according to the order of Melchizadek’. As such, if he does the sacraments of Eucharist, Reconciliation, and Anointing of the Sick after he is laicized they are valid but illicit. (About Baptism, it would be the same as in the East.)
The sacrament of Holy Orders, Catholics would say, imparts an indelible ‘character’ on the soul, as does Baptism and Confirmation, and that effect remains. So we would say the priest is always able to do the sacraments but he doesn’t have the right to do them except with the permission of the bishop. My assumption is that the Eastern Churches in communion with Rome accept this idea also but I don’t know if that is accurate.
Originally, ALL priests of the Catholic/Orthodox church said the Divine Liturgy with the bishops; by 200AD, they were saying the liturgy with the bishop’s permission.
In the Byzantine East (since not all the east is Byzantine), that permission is expressed by the issuing of the Antimension.
In the west, that permission is incardination into a diocese or recent letters of release from the priest’s bishop. A priest not under the jurisdiction of a bishop may not licitly say the Mass.
Under extant canon law, Byzantine priests saying the DL without an Antimension says a valid but highly illicit DL. Illicit for lack of form (violating the prescriptions of the Liturgical Books) and for lack of episcopal permission, but meeting the standards of a valid institution narrative and epiclesis, still valid.
Further, the whole issue of Valid vs Licit is foreign (yet still known) to the Canonical Byzantine Orthodox, for whom licity is the prime test of validity, save for baptism and ordination, and they don’t generally accept non-Catholic/Non-Oriental Orthodox/Non-ACE baptism nor ordination at all, and Catholic, OO, nor ACE except at conversion to Orthodoxy and then as Economia. They subsume the two, validity and licity, into orthopraxis and presume with orthopraxis comes orthodoxis, unless signs to the contrary are present.
In general tho, licity is a subset of validity, and the Byzantine East makes the overlap much greater.