I'll be there on Thursday, if not before. I can confirm the stories, and know the guy that first spotted the axe (Andy Norfolk), but I've never actually seen the axe myself. It's said to be very low on the central stone, and only visible in certain light. I've obviously not been there at the right time in all the years I've been visiting...
Andy is on the Portal I think, he may be able to provide images. If not I'll ask another friend of mine down here who is into photogrammetry techniques. He's working on the St Piran's Oratory project at the moment.