A good idea... but not workable with the current game engine...
the soldiers hands are very much part of his body, and therefore the model selections that go into it...
The hands are fixed into set poses (hence the "bear claw" look to them) which is why it looks odd when the weapon is on the back and so on...
Also, using this method, what happens when the weapon is dropped? or slung on the back? there will be hands everywhere...
With the current game engine, we are limited to keeping the hands how they are now, and careful modelling and placement to prevent the hands from "slipping" into the weapons
Using the anim tool, yes we can create new animations for each weapon, but that just goes to increase the workload on the modders, and the filesize for the users... The amount of coding and the number of .rtm (animation files) for 1 new weapon is unbelievably large... there are at least 30 animations to do (Walking/Running/Crawling/standing/crouching and so on...) and the cpp file would run into 100's of kb's in size (no problems for downloading, but a nightmare to code
as a final point, depending what lod you are in, the face count on the hands (highest detail lod) is 500 faces (for both hands - 250 each...) adding more faces to increase the detail will simply increase the lag :-\ its a "stuck between a rock and a hard place" situation