The machete was clamped to an outdoor workbench and sprayed with water occasionally. The only areas that got really hot were the areas where the blade was cut, mostly in the tang area. Discoloration only near the cuts.
A dremel with cutting discs would work just as well, and might generate less heat. You can take it a little bit at a time if you're really worried about it.
According to the only data I've ever found, Tramontinas are 1070 steel run in the 48-52 HRc range. Cheap as dirt, plenty tough. Relatively thin and perfect for modding. The more adventurous can even experiment with differential heat treats and such.