Headscratchers / Agent Pendergast

In The Wheel of Darkness, why the Hell did Pendergast return The Agozyen to the monks? After learning what it's capable of, and the fact that its very use is a Self-Fulfilling Prophecy (i.e. cleansing the Earth of Human Evil...by turning people who look at it evil), the sensible response would have been to burn it or at least throw it into the sea. Furthermore, you think he'd have terser words for The monk who deliberately let the first thief steal it.