So if you missed it up above, Helen has this arm...

Her right arm... well, that can be turned into pretty much anything - animate or inanimate. In the book she once turned it into a copy of a weird totem pole with vicious heads biting at each other till they drew blood. And of course, as the living blade - which looks like a bar of light - she can cut through the barriers to worlds and kill any demon of any size or level.