Interesting. Your seal dates to c. middle 11th century (the Nikopoios
type is usually from that period) while this Yohannes is an interesting late 10th cent. figure. Moreover, he was a
bishop of the
Armenian apostolic
church who were monophysites. In that capacity, it is pretty much impossible that the seal can belong to him, being a 'heretic' within the empire. But later he did adopt the Chalcedonian creed, effectively 'converting' to
Byzantine orthodoxy. There was not an orthodox bishopric in Cappadocian
Larissa as far as I can find, so your seal must belong to Thessalian
Larissa, which was a
metropolis. Looking in Laurent's Corpus of clerical
seals, St.
Achilles seems to be the
patron saint, but there are is
Mother of God type as well. I would continue to
search for a Konstantinos, metr.
bishop of
Larissa in
Thessaly.
Regards
Gert