An OTF in my hands would be a flip toy, I don't even own an OTF due to the complexity of them, too much to go wrong and too hard to clean. I'd rather start with a better tool or put time and effort into learning to make tools from stone or wood so that I could make something crude if I needed it and didn't have anything else available. As it stands now I can make a crummy hand axe and the occasional arrowhead if I have the right type of rocks available.
One time I used my machete and carved a sharp edged wooden sword out of an oak sapling to mess around with. I fire hardened it, refined the edge as best I could, and went to goofing around. I was able to cut a milk jug full of water in half horizontally with a fast swing, not terribly difficult but I was pretty impressed. I wanted to test the limits so I set up a pine 2x4 and cut along the grain to split it, and, no joke, I split a 2x4 with a wooden sword. While it did tear it up pretty badly I was completely shocked that a thin, long edge of relatively soft material was able to do that.
A fire hardened spear is no joke, one reference stated that fire dried wood is as hard as copper. Based on my experience with that wooden sword I made I believe it would hold a point well enough to pierce hide.