Personally I think it could be neat to do a separate totem system between normal and Ex trials. Ex trials can still yield the weapons, and hand out their own totems for the weapons exchange like normal. But imagine if you had full gear sets based on Primals and other bosses. They don't need to be quite as high in ilvl as the weapons, but I think people would farm totems clearing the story fights if it meant they could glam up as something akin to their favorite bosses. Of course, this would also take a fair chunk of development time, so it's likely not an idea that'll ever meet fruition.