Disclaimer: I am NOT asking how to apply a mirror modifier for weight painting.
I have a low-poly model that I rigged and I am wondering why I can only use weight painting on half of my model, the right-side of it. I think that this is because I have a mirror modifier on the 3D object but am I supposed to apply it anywhere? I don't see such thing in the modifier window.
Another related-question: is it because my model is very low-poly that weight painting is very imprecise? I feel like I can only apply a weight to a vertex, but I saw several examples of smoother paint on low-poly models, I was wondering how.