I've always wanted weapon progression in my home game, for many of the same reasons outline in this handbook's intro: I didn't want the characters to just find legendary weapons, I wanted their weapons to become legendary along with them. But because 5e wasn't designed arount that, I completely improvised it, and the lack of structure/clarity resulted in many arguments, a lot of time spent haggling that could have been spent doing more interesting things, and a general sense of frustration towards loot, for both my players and I.
So after looking around a bunch, I can tell you this much. This addition bridges the gap between the narrative I wanted to push as a DM all along, and the structure that my players need so that they can experience it smoothly. It's going to save my table a lot of time.
[5 of 5 Stars!]