Finally finished the athame! A note on materials, the wood is iroko blackened by burning it, in the Japanese sugi-ban manner, and the steel (such as it is) was tempered for 1 hour at 320C to get the blue-black oxide.
A big note on mystery steels! Don't use them!
At least not unless you do a quench test, which I did not. Hence, the old handmade rasp I had found, turned to be unhardenable, though I tried both oil and water quenches. For this particular piece its no big deal as it a ceremonial item and will not see any cutting use, plus the 320C temper would have softened it a lot anyway. But still... its a shame.
Anyway, another lesson is that when I do decide to make a proper knife shaped like a yari, I will run into countless problems keeping it straight in the quench. This one took a wild upward curve, which I removed easily since it did not harden, but I really do not know what I would have done otherwise. In any case enjoy!