Welcome back

It looks like you have fliped normals, select the faces go to mesh display and reverse.

I've never used the Nightshade UV editor but that to me looks like an auto UV map? I would also not triangulate a model before doing the UV this is going to make your life a lot more complicated.

This kind of model is easy enough to UV map but with this the current topology you've of set yourself up for a bit of a nightmare.

If you like I'll make you a video in which I'll model a knife and UV it. No offence to you because I have no idea if you're doing something specific but this is neither the way I would model or UV something like this.

All the best
David