I wish the coin was a litle more clear but from your picture here is the answer.
Andronicus I AE
tetarteron S-1988
Bust of St. George facing, beardless., wearing
nimbus, tunic,
cuirass and
sagion and holding spear and sheild.
Rev Andronicus stg facing wearing crown,
divitision and
loros and holding
labarum and
globus surmounted with
patriarchal cross in upper right
field manus Dei (
hands of God)
The two key points on this coin is the image on St Georges sheild , it should be a lys and the beard of Andronicus should be split. On your coin both are faintly visable. The partial legend of Andronicus fits and so does the symbols used for Saint George. My next
choice would have been an Alexius 1/2
tetarteron but the coin is too large.
This coin was only minted for two months July and August 1185 before Andronicus was overthrown and then killed. This coin is considered to be siege coinage that was issued durring the preperation of the Norman siege of
Thessalonica ( 6-24 August 1185). Also it is the first time the lye apears on byzantine coinage, it became more common in the 13th century.
Simon
