Justinian's Codex 11.47(46).1

Ut armorum usus inscio principe interdictus est

Imperatores Valentinianus et Valens ad Bulephorum consularem Campaniae

No one shall, without our knowledge and consent,  bear any kind of arms.

Nulli prorus nobis insciis atque inconsultis quorumlibet armorum movendorum copia tribunatur.  364 A.D.

Mosaic of Justinian, San Vitale, Ravenna


Lawrence G. Duggan, Armsbearing and the Clergy

in   the History and Canon Law of Western  Christianity (Boydell & Brewer, 2013) does not mention this crucial text.