Need Help: Character pose

I’m working on making a third person shooter. I cannot find any tutorials or guides on making the players pose change when holding weapons. I have tried changing the mech. but it doesn’t save the pose for holding rifel/pistol. How can I change my character to look as if holding a weapon so I can start working this?

I’m not an expert on the topic but I’m somehow interested for my own game.
Isn’t the “holding” just part of an animation of your mesh ?
I guess you shouldn’t have to change the mesh.

Do you have a rigged and skinned mesh? In blender for example you should have bones!
What is your setup for animations (AnimationController)?