[kronckew]

Nepali Kamis (blacksmiths) routinely heat treat their blades with boiling water as a 'coolant' from a tea pot on the critical heated edge to harden that, leaving the residual heat to temper the spine a bit softer. It takes them years of practice to learn how to do it right. Better they should bend rather than snap, you can bend a soft spine one back to workable in the field, but snapped blade can't be fixed there.