I am coming from Reddit and while currently dead, this seemed to be the largest Elden Ring community. So to kick-start the resurrection, here's what even Reddit called my most-returned-to-post. This thing has been open as a tab in my browser for a year now.
My understanding is that the scaling math is independent of weapon level, but of course the more you improve the weapon the more important and noticeable scaling becomes.
The actual breakpoints are a little more complicated than this nice picture but it's "good enough" for my purposes. More at Fextralife