Thanks for nothing, I'll start learning python :D (No, maya's bevel can't do this. It does weld at overlaps, but stops all the other edges in the process)
If you're feeling that brave I can suggest a possible avenue of research.. Look at straight skeleton / median line algorithms. They tend to be implemented in 2d and within a single ngon but will allow you to determine where intersection points between bevels lie on a given ngon. That information could be used to weight…