Exporting, Cutting, Importing Mesh with Skin Weights?

[CurseOfDarkness]

Hi, I posted this in a mod's comments but it's probably not the right place for it so I figure I'll try to ask here..

I'm trying to export some mesh from one Nif file, cut it in a 3d program, and then reimport it into another Nif file but as I've noticed this doesn't update the skin weighting.

What's the proper way to go about this so that the skin is weighted correctly still? I know how to reattach the texturing just fine - I just need information on exporting/reimporting mesh with weighting if anyone would be so kind to guide me through it. Thanks

To get an idea of what I'm trying to do.. the Nord Hero Armor has no pants but there's a mod that allows it to have pants. Unfortunately the mod that gives pants also has a clipping mesh piece that can't be erased without causing the underlying skin mesh to appear to have holes (because the skin mesh is chopped; normally it wouldn't be seen).
So what I'd like to do is export the no pant's models skin mesh and cut the legs off for only the upper torso bit, then import that into a pants version. When I try this, the mesh gets tangled..

For those thinking there's an easier solution, I've tried brushing the pants back into the no pants version and it causes the leg and groin area to show through the pants and just looks wrong. I'd like to learn how to do this for a couple reasons. Maybe I'll make some armor meshes for the community if I learn how to do this.

If you can help in any way, please post! Even if you just link me to a tutorial that may potentially contain the answer. Thanks.

This is close to the kind of look I want, but you can see that leg is showing through the pants. It's a lot worse when I pan the camera around.
http://imageshack.us/a/img28/7813/2013050400007.jpg

Clipping armor piece that covers up the art on the chest piece.. (I'd rather have the neck holes or leg clipping than this; this is the worst version imo). Also ignore the chainmail and leather clipping - that can be solved with transparency layer easily (see other screenshots where it's hidden).
http://imageshack.us/a/img547/8527/2013050400003crop.jpg

Best version wearing pants, but then has holes around neck:
http://imageshack.us/a/img211/4448/2013050400004crop.jpg
(This is the CLOSEST to what I want it to look like, save the fact that there are holes at the neck. Again, they are a lot worse when I pan the camera around.)

Edited May 8, 2013 by CurseOfDarkness

[CurseOfDarkness]

Should I be posting on nifskope forums? :\ any nifskope pros around? -.-

[gawan]

Sorry but except adding some transparency, I'm just a noob with nif. You should ask some more experienced moder. Maybe the author from the tutorial I used : http://skyrim.nexusmods.com/mods/35342/

[CurseOfDarkness]

Hmm I think it's a different issue because the skin mesh has holes when I make a particular part transparent ->

The 2nd pic I posted shows the piece I want to remove because it clips. however if I remove it the neck has hole and those are there because the actual mesh in the nif is cut. The 1st pic shows what this would look like, as far as the upper torso is concerned - but then there's a problem where the leg clips because the skin mesh provides more mesh than I need.

So I need to import a mesh that only has upper torso (because hiding the armor piece is the easy part), and I don't know how to do that. :\