This is a great guide LaughingLeader, you should add it to the wiki.
Funny you should mention it, I wrote up an initial draft for an Item Progression guide today: Item Progression (Larian Wiki)
Thanks for the guide LaughingLeader. This is a valuable insight into the how the progression should be defined for custom items in the game.
You're very welcome. Hopefully that sheds some light on what to do to get new items working in the game.