Unlike most other ritual tool consecrations, the one for the athame should be performed during the waning moon. The ritual is also somewhat more complex and takes longer to complete.
You will need three cups of boiling water, one teaspoon of chili powder, poppy seed, Dragon's blood, henbane, and rue. You will also need three drops of your own blood (you can get a lancet from the pharmacy - don't use anything else as it's not only unsanitary but you risk contaminating the blood), a wooden spoon, a charcoal/coal fire (charcoal in a barbecue grill is suggested), an oven glove, incense of your choice, a bowl of water, and a magnet.
When ready to begin, boil the three cups of water, add all the herbs along with all the drops of blood. Stir well, cover and put to one side to cool.
Prepare and light the fire. Once the charcoal is hot light the incense from it. Pass the athame through the smoke and say: By power of air light and free I cleanse you of negativity.
Sprinkle the athame with water and say: By power of water clear and pure I cleanse you of energies past and obscure.
Put on the oven glove and heat the blade until it is red hot and say: By power of fire, be cleansed and free from your past life of mundanity.
Plunge the blade three times into the herbal infusion you had put aside and say with each: Tool of steel, your orders be to banish all things I ask of thee.
Throw the herbal infusion onto the fire and dowse it thoroughly with water until it is definitely out.
Get your magnet and use it to stroke each side of the athame blade (in order to magnetize it) while saying: Tool of steel, your orders be to invoke all things I ask of thee.
Continue this process until the blade is capable of picking up small nails or paper clips etc. This process may take quite some time (though it's usually quicker than you might think) and it won't hurt to take a break.
Once the blade is magnetized you need to decide how it is to be decorated. If you wish to carve (or paint) runes or other symbols on it then do it now. Else wait until after the next stage.
Dig a hole in the ground that is deep enough to bury the athame point down. Cover the athame with earth and as you do, say: Grounded you are with the power of earth, absorb its stability, richness and mirth.
The athame should be left buried for sevent-two hours and then dug up.
Wash and clean the athame thoroughly with soap and water. Dry it well.
Finish decorating if necessary.
Wrap it in a black cloth or sheath until you are ready to use it.