It is significant in the Key of Solomon that the magick circle “may be marked either with the Sword or with the Knife with the Black hilt”, as this clearly introduces the idea of casting the circle with the sword or athame. The use of magick tools to cast circles has a long history extending back to the ancient world. The use of the wand for this purpose, which is given as an option in the Wiccan tradition, is prominent in the history of magick circles.
In the fifteenth century the German Abbot Johannes Trithemius described the use of an ebony wand to trace the circle whilst speaking the conjuration in The Art of Drawing Spirits into Crystals. This short booklet was a small part of the material included by Francis Barrett in his famous work The Magus in 1801, which provided a wealth of material from the grimoires, Qabalah and on natural magick in an accessible printed book in English for the first time.
In the Grimoire of Pope Honorius the writer suggested that the magick circle should be marked with charcoal which has been blessed with salt, or as an alternative with chalk, the latter being the more popular choice for later magicians.
One of the later grimoires makes specific reference to the use of the knife to trace the existing magick circle upon entry within. This is the Grimorium Verum (“The True Grimoire”), a latecomer to the grimoires, being dated to 1817 in its earliest form. It is largely derivative of earlier grimoires like the Key of Solomon, but the knife reference is interesting in the context of Wiccan practice in its use to trace the circle which has already been drawn:
“Once inside, trace your ring (or circle) with the knife of the art.”
Extract from: Wicca: Magical Beginnings written by d’Este & Rankine, 2008 (Avalonia.) PB / Kindle @ https://amzn.to/3Ay4HJr. Shared here with the intention to inspire and inform the now and future generations interested in Wicca and other Pagan traditions inspired by it.