The athame can be used to cast the magick circle, call the "quarters" or elements, and is part of many an opening ritual, handfasting (wedding) or initiation rite. It is associated with the element of Fire and the South. It is customary in some traditions to have your blade given to you as a gift. Some Witches or ceremonial workers give their tools a magickal "name". (This practice has become a common reference in many role playing games and fantasy novels.)
Almost all materials written state-and most Witches/Wiccans, with the possible exception of the Sax Wiccans, agree- that magickal tools should not be used for any other purpose than ritual work. Often the blade is left "dull" or unsharpened because of this. (Another blade, the "boleen", with a white handle is sometimes used to harvest herbs or carve symbols, but not used for ritual work.) Some Witches will not let their tools be touched by anyone other than themselves. Some covens or working groups share common tools. It is, other than for those who are dedicated into a specific Tradition, what you are comfortable with.