First, I'm new to StackExchange, so I apologize if I'm posting in the wrong area...
What is the strange visual element emanating from the hammer in this picture? It looks like an upside-down white flame. I wondered if it was light reflecting from the hammer handle, but it looks different from what I'd expect for that, with little flecks present outside the arc that a light trail would create.
The photo is of a metalworker in action, and the hammer had just struck the metal when I took the photo.
What is this?