"Searching for a dropped athame at night during an outdoor ritual is the ultimate test of one's faith."
An athame is usually kept dull because once it has tasted blood, it ceases to be a symbol of one's will and becomes a weapon. Or, in more poetic terms, it is no longer consecrated to the service of the Goddess, but to the service of the God of War. The best that can be done for it (or any other desecrated magical tool) at this point is to bury it and give it back to the Earth.
Interesting, then, that a Nethack wizard begins life fighting with an athame.