Greetings in that Divine and Most Precious Name of Our Lord and Savior Jesus Christ!
^Yes, in the Alexandrian Church Deacons are allowed to serve the blood, not the body. But, what do you mean by "legalistically speaking they could?"
That while we do have the rank of Arch Deacon, there are not lesser ranks and responsibilities like in the Coptic tradition. As I understand it, any ordained Deacon can serve the Blood if need be, but traditionally only those trained or experienced tend to, and in all functionality, younger or lesser experienced Deacons tend to do a bit of the more "menial" aspects of Altar service during the Liturgy. I understand that in the Coptic Church there are several kinds of Deacons, but only the "full" deacons can serve the Blood, but in the Ethiopia tradition I don't believe we necessarily have these demarcations of rank aside from Arch deacons and regular deacons. Sometimes priests even serve as Deacons, usually they are the married priests (Kesis) however sometimes even Monk-priests serve as Deacons and dispense the Blood. Technically speaking, no Ethiopian liturgy can be celebrated without 3 priests and 4 deacons, however in practice this only occurs in the kinds of Churches that have such numbers. In lesser parishes, people make due, and I've attended Divine Liturgy with literally just two priests and a handful of laity, with one priest celebrating and the other serving as Deacon. Again, the canons say there must be three co-celebrating priests and also four deacons.