User blog comment:Yuu Chikuwawa/About 9 Sacred Treasures/@comment-24570336-20151104110421/@comment-24570336-20151105070424

Oddly, Sacred Gem's lore is referencing the Sacred Blade's lore but it did not refers itself as the Quatre Marinus where the Sacred Blade did. I do agree that the Sacred Gem effects suit Duran more than the Sacred Blade.

It's possible that Gumi intended Sacred Blade to be Duran's Sacred Treasure while Alim did for Sacred Gem, so they localized and switched them around. Judging by the art, the Sacred Gem appears to be implanted into the Sacred Blade, so that could be why those two have similar lores. Nevertheless, his lore states Sacred Blade in Global so we'll stick to this.