Regarding point  above VIRBONUS is an attested early Christian name A quick google yielded the following examples  A bishop named Saint Virbonus who attended the Roman Council of  Source D Pringle A group of medieval towers in Tuscania in Papers of the British school at Rome Vol   pp   A Roman abbot named Virbonus ca  Source E Wellesz Recent studies in western Chant in Musical Quarterly Vol  no  April  pp   I note that the Thetford treasure also has the inscription VIRBONE VIVAS Given that all the other dedications are to persons it seems more likely that this one is likewise rather than the vague dedication good man