The Eye of God
His name's meaning is considered to be "Friend of God". He's speciality is to bring justice, equality and fairness. He is concerned with the powers of balance.
He is considered to be the angel of earth and the guardian of 2nd (and/or 4th) heaven. He watches the behavior of other angels. He is also responsible to bring other angels to role.
Historically; resemblances can be found in Babylonian culture as "Rag" (some translations says Ragumu), and in Sumarian as "Rig" which means to talk or speech. Thus, in those cultures as well; he represents balance.