I've seen them do this on houses in Japan, never thought about doing that to a guitar headstock. I think Ned Ryerson has done something like this, but to bodies. Me, I'm too chicken.
I can't remember what they call this technique, but if you could figure out the term it might be worth the search, it's something like Shugi-ban.
Sir, I like the cut of your jib.I believe it's Shou Sugi ban. A preservation/burning technique. The masters that practice it in Japan spend half a lifetime or more refining their craft. What I did to the body and maybe headstock is by comparison, just burning sh*t.
It'll void your warranty