Hola. Just find in roman lot maybe byzantine, not much details, 17 mm and 2,30 g. Can give me a clue ?
Actually, the size and weight suggest more the Manuel half tetarteron, Sear 1980. Looks pretty much the same. The only other option I can come up with would be the John II Comnenus (1118-1143) AE half tetarteron Thessalonica SB 1955, which also looks similar. But I'm pretty sure I see MAN on your coin
It is Manuel, if it had been John then the Saint would be another waring saint, St Demetrius . However his shield is not round, it has a triangle shape. The coin based on size and weight I would say it is not a full tetarteron. It is a half.