Fith-faith is a small image of someone made of either wax or clay. Its use is similar to that of a voodoo doll, puppet, or pins and needles. The image is used to focus one’s energy, for either a good or bad purpose, upon a particular person. Traditionally, accordingly to the times, pins, needles, or nails were driven into the image to direct a magical effect or personal will-power to achieve the desired purpose upon the intended victim. The same practice can be used to achieve healing or binding somebody from harming others, even himself at times. (This is associated with sympathetic magic.) A.G.H.
Grimassi, Raven. Encyclopedia of Wicca & Witchcraft. St. Paul, MN, Llewellyn Publications. 2000. p 136