Thanks to all for the replies! (First of all, one of my considerations for palaeo-Hebrew, which I neglected to share, is that this seal was bought from an Israeli
collection, but with no find spot specified.) But I see Aarmale's second confirmation it is not likely to be Hebrew. I
had a look at some Armenian/Syriac inscriptions from late
antiquity and I don't see much to go on there either.
Any script other than Latin and Greek would indeed be unique in combination with a
christogram. However, to interpret the
legend as Latin or Greek would imply that it is very, very crude. This does not align with the rendition of the
christogram, which is very neatly and 'professionally'
engraved in the seal stamp, seriffed and all. That variety in craftmanship on a single die is hard to explain. If the engraver
had no knowledge of the Latin or Greek alphabets - as could be seen everywhere in public inscirptions - then how did he engrave such a nice
christogram? Or did he deliberately blunder the
legend, as on 'magical'
amulets?
Lastly, I do not think a combination of a
christogram and Hebrew should be excluded as an a priori impossibility. The
christogram does not even need to be
Christian (which is something the
legend might make clear).
Regards
Gert