Blender - Strange texture stretching

[Maui]

Heya, I'm trying to port a falmer into JKA but there's a problem which I also get with other characters I'm trying to port.

 

 

When I rotate the arm up, you can see that the texture is stretching out. I know that these models aren't made for these strange arm movements.. but how do fix that?

 

 

Also, the shoulder part.. does it look decent or can I do something to improve it? (I'm just a frankenstein modeler)

[AshuraDX]

If you properly blend the weights across your geometry you will get a better result.

[mrwonko]

And you might be able to move the vertices around on the uv map a bit to space out the area that is distorted.