From A Wiki of Ice and Fire
The Fiery Hand, known also as The Lord of Light's sacred soldiers and defenders of the temple, is a group of Warriors that protect the Red temple of R'hllor in the free city of Volantis. The Fiery Hand are all Slaves of R'hllor and wear ornate armor over orange robes. They wield spears whose points are shaped as writhing flames.
Their number is one thousand; never more, never less. There is a saying: "a new flame is kindled for every flame that gutters out".