The website I was using was using percentages, that's why I said 60% instead of 0.6. That range change was made either after or concurrently with the other buffs. I totally agreed with the narrowing of that range, even though I had it at a high level by the time it was actually done. However, like others, I never used it more than once at low levels, because it's didn't do as designed that early, that is why the gun was unpopular. Unfortunately, BW made popularity as big a factor as if the gun really was OP or not as a big factor in it's nerf or buff decisions.
Wraith was buffed gradually over time, the weight buff was right there in the middle. The damage range between I and X was always the same as it is for every* weapon: I * 1.25 = X
Honestly, I don't remember things being the way you do, and I certainly don't remember there ever been anything out of the ordinary in the way Wraith scaled. Originally it was simply underwhelming. People complained that it wasn't as impressive as an UR shotgun should be. Then it got buffed and bufffed and buffed and buffed and buffed and over time people started to use it more and more. I don't remember weight ever being a significant issue, though after that got buffed, it certainly became even more useful for casters at lower levels.
(*: there may be outliers, I haven't checked literally every weapon)