There's no close-ups of the ANH sabers to know for sure. The ESB/ROTJ hero is one of the best photographed pieces thanks to being found by RPFers. That said, the shroud on it, like Roy said, is so oddly unique being steel that it's never been found on an MPP in the wild with the same type of shroud.
Since we know most of the ANH props were restored and returned I'd hazard to say that the ANH versions were probably wrinkle-painted.
Since we know most of the ANH props were restored and returned I'd hazard to say that the ANH versions were probably wrinkle-painted.