Well, there are bronze brazing rods, so maybe they got it just hot enough to melt the rod and for it to stick to the flash. I dunno. Or like you said, maybe just used the tungsten to melt the chrome away. If you do it fast enough, the heat will stay pretty localized, so that might explain the lack of discoloration around it, plus, some of it could be easily polished away.
And yeah, all I see are Maul parts when I look at her staff/saber.