The Athame (Ritual Knife)
The athame isn't used for cutting purposes but for directing energy raised for rituals and spells. The knife does not need to be sharp, and the handle is usually either black or another dark color. Black absorbs energy and a little of the energy is absorbed into the handle every time it's used. Sometimes energy is raised and stored in the athame for use later. The handle or blade of the knife can be engraved with runes if you wish but it's not necissary. A sword can be used also it has all the same properties as the knife but can be difficult to use indoors.
The athame is a tool of change linking it with the element of Fire.
It's phallic shape links it to the God.
Finding or Making an Athame
Unless you have access to a forge making an athame is out of the question. Finding one is much easier, any knife or blade store usually carries a selection of medieval weaponry including ornate daggers. These daggers range from $10 to hundreds of dollars. Some of the cheaper ones work quite well, try to find one that dosen't have any plastic parts. If you can't find a blade store try mail order of the internet.