We can combine the best of both worlds of the omnissiah and the requisitorium- the ability to choose specific item properties, and the need for engagement in core gameplay to achieve those goals.
My suggestion is to be able to choose a specific property for your weapon, and that property starts at rank 1. To improve that property, you just play the game normally. No need to play waiting games or pulling the slot machine handle. You just need to go into missions and complete tasks akin to the requistorium, such as killing a number of scabs or monsters, or performing tasks related to the property.
For instance, ranking up a bonus crit chance property on a weapon could be an x number of crits done for each rank. Ranking up blessings that require consecutive hits can rank up ‘hit an enemy x times, y amount of times’ or somesuch.
In this way, playing the game the way you want to play it further improves the way you want to play the game. Really quite simple, and engaging with the core gameplay loop.
The requisitorium can be reworked as a system for people to order in a specific weapon of their choosing with specific stats and properties, which can then be taken to the omnissiah to unlock those properties in the way I mentioned. So, in that case, you’re given a gray weapon, but with guaranteed properties of your choosing as you use it and upgrade it. So, plasteel and adamantine are still used to increase an item from gray to blue, etc., and unlock the properties held within the item.
What does this mean for the item shop? Well, that can still be used for non-premium skins and the such. I believe the primary interactions for progression really ought to just be between the requisitorium and omnissiah.
I also believe this should meld well with lore and not literally ‘crafting’ anything, but rather a series of improvements on something that already exists within the weapon, which appears to be the direction the dev teams wants to go in, but this way interacts directly with the core gameplay and with far greater player agency, adding in a touch of skill-based interaction.