I have seen many similar questions but haven't been able to find an answer for my specific issue
As you can see in the image, the arm on the right is properly painted, and the arm on the left has NO weights at all. I want the left arm to have the exact same weights as the right one for the corresponding bones.
I'm aware of the symmetry options, which are useful, but require me to repaint the bone. I'd like to just copy over the existing weights to the other side