Peter Keith Squire, who helps keep Stonehenge secure at night, has been out with his torch dagger spotting again. He recently sent me a stunning photo of the dagger on Stone 23 - http://www.sarsen.org/2012/10/new-photo-of-stone-23-dagger.html.
So now have a look at this photo I took of a carving on Stone 4, taken with his torch shining vertically down.
There seems to be two holes above a faint shaft that then goes down into more familiar axe shape. Click any photo to enlarge them to make them clearer.
The Laser Scan has a Luminance Lens picture of Stone 4 on which I have highlighted it as well.
But the official results only pick up the axe head - F693.
I must have another look at the actual stone but from the comfort of my desk it does look very like the dagger on 23 and not just another axe head.
Dagger on Stone 23 and for comparison some of the axes and daggers on Stone 53:
On the left is the newly discovered "dagger" F600 and above it "axes" F596 and F601 which have a swelling on the handle. There seems to be a continuum between axes and daggers.