Ok here is an working & slightly updated source .blend and it's corresponding .md5mesh.
Would be nice if it was included in the svn.
Note that it does not contain the animations (except one to make the exporter work), thus it relies on the old .md5anim until someone properly re-imports those in the same .blend.
I slightly updated the mesh itself, and improved the mesh weighting, but IMHO it isn't very visible in the game and the mesh turned out to be very difficult to improve, because it has a very messy tri-only topography. Attached is also a quadringulated and slightly updated mesh .obj (I had to re-triangulate it in the .blend however for the exported to not throw out garbage). But as you can see, unless you redo the entire UV normal map etc, you will have a very difficult time improving that
mess mesh... so I guess the best option would be to completely redo the hud_hands mesh with proper quad-topology (I am not planning to do that currently though).
I hope this helps someone in the future to improve RE further

P.S.: All of course under the CC-by-SA, no need to credit me for the small changes and the reverse-engineering I did.
“Reality is that which, when you stop believing in it, doesn’t go away.” - Philip K. Dick