Complex sentence: It is only known that it was restored by "Protosebastos" John Komnenos, son of Andronikos I Komnenos and brother of co-emperor John, who died fighting in the battle of Myriokephalon in 1176.
Split into simpler sentences: It is only known that it was restored by "Protosebastos" John Komnenos, son of Andronikos I Komnenos and brother of Coemperor John. He died fighting in the battle of Myriokephalon in 1176.