Would brazing generate enough heat to produce said marks?
With only one inside photo and one close-up outside shot and a fairly long distance outside shot to go on, it is hard to identify the method with which they attached the legs. The outside photo shows white lines away from the actual attachment area, maybe residue from preparation for attachment, leading to my last post. Brazing was one of my first thoughts after actual welding (whether stick, mig, tig, or other, but the picture looks like someone mixed up a two-part chemical and smeared it on the skillet and then pressed the leg into the mass and let it cure.
Really brings out the redneck skill factor.