What is an "athame"?

I had never bothered to look this up until today, and found this interesting etymology on the Merriam Webster's Dictionary. Going to chuck this accursed thing right out of Father Mateo's deck! (Or maybe this is why he's Doomed...) https://www.merriam-webster.com/dictionary/athame

athame noun atha·​me | \ ˈa-thə-ˌmā , ˈä-; ə-ˈthā-mē, -ˈthä-(ˌ)mā
plural athames

Definition of athame : a usually black-handled, double-edged dagger that is used in some neo-pagan and Wiccan rituals

The organizers ask that no athames, swords or similar items be brought into the park. — Santa Fe New Mexican, 8 Sept. 2001

First Known Use of athame:

1967, in the meaning defined above History and Etymology for athame

alteration of earlier arthame “knife used in casting spells,” borrowed from French, alteration of artave, borrowed from Medieval Latin artavus “small knife, penknife”

Note: The introduction of the word athame is credited by students of modern witchcraft to the British author Gerald Brosseau Gardner (1884-1964), who used it in his book Witchcraft Today (London: Rider, 1954). Athame appears to be Gardner’s own variation of arthame, a form of the word to be found in Witchcraft, Magic and Alchemy, a translation (Houghton Mifflin, 1931) by J. Courtney Locke of Émile Grillot de Givry’s Le musée des sorciers, mages et alchemistes (Paris, 1929). Givry in turn extracted the form from a manuscript of the Key of Salomon (a textbook of magic extant in many versions in circulation since the 16th century) entitled Le Secret des secrets, autrement le Clavicule de Salomon ou le véritable Grimoire (Bibliothèque de l’Arsenal MS. 2350); the word arthame can be clearly read in a reproduction from the manuscript on p. 104 of Witchcraft, Magic and Alchemy. Arthame—like arthanus, arthano or arthany, recorded in a 16th-century English manuscript of the Key of Salomon (British Library MS. Sloane 3847, dated 1572, transcribed by Joseph H. Peterson on the website www.esotericarchives.com)—is a miscopied vernacularization of artavus, a Medieval Latin word for a small knife. According to Joseph Peterson, artave is found in another French version of the Key of Salomon (British Library MS. Kings 288) and artavus in Latin manuscripts of the Key (see Peterson’s edition of Liddell MacGregor Mathers’ English translation of the Key on Peterson’s website). The word artavus is found in Latin manuscripts from about the 11th century onward, originally in Britain. Dictionary of Medieval Latin from British Sources (Oxford, 1975-) notes its occurrence in Historia Brittonum (“History of the Britons,” a largely pseudohistorical compilation whose earliest parts may have been composed in the 9th century) and in an 11th-century Latin-Old English glossary attributed to Ælfric of Eynsham (where it is glossed by cnīf, while the more usual Latin word cultellus is glossed by sex), among other places. The etymology of artavus is quite obscure; -avus is not a Latin suffix, so the non-philologists’ attempts to derive it from Latin words are of no value, and the word has no evident counterparts in Celtic or Germanic.