That's an anonymous seal depicting two warrior saints.
Obv. shows Saint George [O GE]-WPGIO' (The accent is an abbreviation mark, peculiarly only for the letter 'C'!). The
rev. shows Demetrios [O D]H/[M]H - TPIOC (can't see these last letters clearly from the photo though). He is holding a spear in r. hand and
his l. on hilt of sword set on the ground. I'd date this one 12th century.
Regards
Gert