Female mirror guards of an African king

In the African galleries at the Field Museum in Chicago, I came upon two ladies I greatly admire. They are bodyguards of an oba, or king, of Benin, complete with armor and helmets and fierce expressions.
   Their weapons, or rather shields, are what seized my attention. They are holding up mirrors. These are intended to deflect any intended harm from the king and return it to the sender.
    The mirror defense against psychic attack is well-known across the ages, and the mirror is an ancient tool of shamans. The mirror ladies of Benin must have been formidable psychic bodyguards.