Rigging issue with custom player model

Hi, I’ve been trying to fix this problem with a model port I’m doing. I am having issues only with the hands. (it’s mostly the left hand, right is fine)

Everything else has turned out okay and this is my first rig.

Here’s a screenshot of Model Viewer with the human animations on the model:

I believe the problem might be because I have resized/reshaped/rotated mesh or have not properly weighted the model.

The model program I have been using is Blender. (if that helps)

If anyone has any possible solutions I am open to them all, thank you.

Modelling forum: http://facepunch.com/forums/40

Thank you for letting me know, I knew I had posted this in the wrong place.

If someone could delete this thread, I have moved this over to here.