Not sure if bug or me just misunderstanding the feature. But the Demon Lord +3 all per Ancient item bonus. Gets +3 every time you upgrade one of your equipped Ancient items as well. So I currently have +48 all.
for each item (times its rarity level) you get the bonus. so in max. 6 items with rarity max (6) -> 108 each... may be a bit strong - on the other hand what are the chances you find them all ^^'
