This is barbarian cultural armor, meaning only barbarians may craft it, and only in their cultural forge, located in Halas. There are no deity restrictions on crafting this. However, as the item shows, appropriate class/race combinations that worship the Tribunal may equip this. These combinations include non-barbarians such as humans and half-elves.
Thus, since your barbarian friend does not worship the Tribunal, he would not be able to equip this bracer. Not worshipping the correct deity is as restrictive as not being of the right class or race.