http://en.wikipedia.org/wiki/Athame
According to this article, mages should even be able to use swords
On the other hand, the athame stands as one of the four elemental tools in Wicca; traditionally standing for fire, as does the ritual sword. (From the known origins of Wicca, with Gardner's own Book of Shadows, the athame represents fire; where the wand corresponds to air. Other varieties of Wiccan practice may switch those two around.) The other three elemental tools are the wand, the pentacle, and the cup or chalice. These four magical tools correspond to four 'weapons' of significance in Celtic myth - the sword, the spear, the shield, and the cauldron (and/or grail).