Playing Boulder Toss barb, Dual Wielding “Arreat’s Law” and “The Three Hundredth Spear”.
I had been using both for a little while before using the Cube recipe: Curiosity Of Lorath Nahr.
I upgraded my “The Three Hundredth Spear” to Primal then upgraded my “Arreat’s Law” to Primal a little later when I acquired the materials.
It’s now saying "You cannot equip more than one of this item when trying to Dual Wield the two weapons that I was able to before upgrading them both to Primal.
Edit: I have restarted the game multiple times without either weapon equipped and am able to use one OR the other and equip a completely different weapon in my offhand.
When they had this as a Seasonal Theme, they made it so you could only have 1 upgraded Primal equipped, otherwise everyone would have Primals in all 13 spots in a week. When they made this into a cube recipe, they kept it the same, only 1 upgraded Primal may be worn no matter what slot you use.
Therefore, it is not a bug. This is how it is designed.
Indeed.
They really should have this red and bold in the cube description.
Having important mechanics like this only described in the patch notes is pretty bad design, but I guess misleading descriptions is now seen as a feature in the diablo franchise, part of easy to play, hard to master?
Unfortunately, the game is entering its terminal stages. Very little will be updated. Even the game guide isn’t being updated with the new recipe. Unless there is a serious, game-breaking bug, nothing will be fixed.