Oof gambryo is struggling here for this haha.
Let me think of the various times I've had a similar problem, I did not run as many mods but maybe this might help?
Going to assume you already have MCM and UIO or Unified Hud etc. I'm not sure about your game, but generally messing with UI in New vEgas is very touchy. You have to constantly overwrite things in a certain order otherwise it wont work. With the weapon menu, did you have any other UI mods installed alongside it? Because I had a retro UI texture installed for the whole game UI and installed it along with MTUI, however because of the way certain scripts save and work if your game crashes or you uninstall there are a few files left over from it just stay there, no matter what and screws with the xml files.
Try, if you can, getting rid of most of your UI mods at first aside from say MCM etc, see if the game loads, make a clean save with just minimal UI mods, then one by one reinstall with UIO or Unified HUD as the absolute last thing. I know those two mods are supposed to do the same thing, but for me when I installed UIO it did nothing for my errors, installed Unified instead and it fixed everything. Good luck!
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