Third Person Aiming

Ok so right now I am using the Invector 3rd person controller and I am having lots of difficulty when it comes to aiming, specifically on the animation side.

Basically, the third person controller already has all the ik setup; even I figured that out with my lack of ik knowledge. When the camera is on an aiming state, it zooms in and the characters body and head will rotate with the mouse's axis like a normal aiming system in a third person game. By default, this aiming state is with no gun animation. If that doesn't make sense then here's what I'm talking about:

By default, if you click aim, the camera just zooms in on the character and the locomotion enters a strafing blend tree. That already takes care of all the things I need to accomplish. If I look left, the spine bends and the head does as usual.

Now I already made a weapon system that works, so I know the issue isn't through there. When I pick up my pistol (again, this weapon system is already taken care of) , the idle state is over written. Basically, what I mean is: When the weapon is picked up, the 4th layer in my animator, called "Item Layer" (I made this) will be called and will play an animation called pistol idle. Basically when the character is idle (BUT NOT AIMING) his pistol will be held down. This animation's weight is set to 1 every time the character is idle WITH a pistol. Ok now that I explained that, I can explain my problem

My problem is that when I click aim, my code tells the character to do a pistol aiming animation. Problem is: the characters arms aren't fixed right. It look's like my character is not aiming properly towards the reticle. In fact, you can barley see the gun when he is aiming down. I guess my problem is that I need a new animation with different arm positions, but I can't find any. I have looked at all the pistol aiming animations on mixamo, none of them work. To add on to the problem, putting an upper body masks also kind of alters the position of the arms when aiming down in a pistol.

In summary all I ask is: How can I change my pistol aiming animation? Do I need to edit one it on blender just for the arms and export it as a new animation? Because I have already tried this and I can't figure it out. There is no way to right click on a key frame, and edit the arm rotations. What other solutions do I have to make a working aim animation?