A go at making a walkthrough of editing/combing vanilla armor parts in blender and exporting them out again. And cleaning them up in Nifskope. Maybe you'll find some use in it. Be advised it is long, relatively speaking, I probably repeat myself, and some info is probably not 100% accurate.
The Nexus Forums for their general guidance and helpful users. Without whom I'd probably never have figured out how to properly mod New Vegas.
Civfanatic Forums for their various Blender tutorials. Without which I would have never learned how to use blender or nifskope in the first place.
Donation Points system
This mod is not opted-in to receive Donation Points
This tutorial should show you the absolute minimum that is required to import a vanilla nif into blender, edit it a little bit, then export it back out again, and clean it up in Nifskope while still being usable in game. I know there are other better tutorials out there that cover this but they all kind of fall off at some point. They don't go over some minor point that may well be where the issue lies. Well this tutorial has that issue too. Hopefully it is just in different areas.