what potential of the item do I need to put 2x2 bound focus shards in it?

[hohohohoololo]

Assuming I got that correct, you are trying to put two greater spell focuses on a single item, which, is impossible.
Spell focuses take the prefix slot. Each item is limited to a single Prefix and a single suffix, in addition to those two weapons and armor can have an enhancement value added. Each of those modifications is in addition to the base item's stats.

I could not test it by myself (because of low crafting lvl) but I hope that you are wrong!:


tnx for answer, anyway!

[Hutoth]

I could not test it by myself (because of low crafting lvl) but I hope that you are wrong!:


tnx for answer, anyway!

You cannot craft an item like the one on the right.

[hohohohoololo]

You cannot craft an item like the one on the right.

so I always should switch my equipment?