User blog comment:B214/Question & Answers 5/@comment-207.96.205.2-20160517060930/@comment-1359322-20160519040314

There's no actual evidence on your side that states that the Evil Pieces converts the soul. In Volume 12 it only said '''the EP is connected to the soul, it never said it converts/transform the soul. That's your own speculation'''. The Boosted Gear is connected/attached to Ise's soul too but Ise's soul is not that of the Boosted Gear. Same logic and reasoning as that.

For starters, the Evil Pieces and Brave Saints are made from the same material, the crystal in Agreas, by your logic then all the Reincarnated Angels like Irina should have the soul of the Devils too, which is not the case as well.