little doubt about infused back armor
You will lose the versatile simple infusion, and you will gain an “Agony Infusion Slot”, which you could then put a +1/2/3/4/5/etc Agony Infusion into that you can acquire off of the TP. When you first upgrade your backpiece it will be worth +0 AR, and you will have to add another versatile simple infusion and Agony Infusion to it in order to bring it back up.
If i do it i will lose the +5 vers. simple infusion but i will gain a +5 AR due to the infusion that the infused armor bear “per se”, right?
This used to be how it works, but is no longer the case. It used to be that it would come with +5 AR inherently and an empty offensive/defensive infusion slot, which you could then put a new versatile simple infusion in for a total of +10 AR.
Now when you infuse your backpiece, you get a new second “Agony Resistance Infusion Slot”. Both of these slots start empty. (So you start with +0 AR). You can still put a new versatile simple infusion into the offensive/defensive slot for +5 AR. With the second slot, they take the new Agony Resist Infusions which you get at least one of a +1 AR at the end of every fractal, can buy more on TP, or upgrade lower numbers into higher numbers via artificer crafting. These two slots are separate and stack.