Athame is usually a ritualistic dagger(not a weapon) to direct energy. It mostly isn't used for drawing blood. While a dagger generally is a weapon, an athame is more like a tool to direct energy.
An athame can be sharp as it may be used in ritual cuttings. It is typically a dagger or knife that one chooses to use specifically for ritual work. It is not to be used as a weapon however in an emergency I don't think it is sacrilegious or seen as negative in the eyes of the gods. A sword could be used as an athame particularly for casting the circle. I do not think a mace or axe would be good substitutes for an athame however an arrow, spear, or scythe can be used like an athame during ritual.
Below are some links to athames that may interest you;
