Is there a possibility of creating pieces/set armor that applies xp bonus for characters? Previous versions had xp boosts while leveling. I recall a set of armor that was account bound that could be used for any character from level 1 to whatever and scaled to level. Maybe something like this being available after campaign is completed.
Nah, they confined that to “Elixers”.
Also, there are no sets or unique items at all.
Blizz just didn’t bother including anything that made diablo good.
There are unique items - they appear in T3. They aren’t the same as previous Diablo games where you could only own one of that item. Instead they are unique equipped, ie you can only have one of that item equipped. You can have multiples in your stash/inventory.