Thread necromancy here, but I figured this was some good information. For all the items in the full Japanese list, there are items highlighted with a purple/pink background. Those items are Dark Arisen items. For example, 701 グランシスフランベルジュ is the Gransys Flamberge. Glad I'm weeb enough to know my katakana. Hope this helps.
EDIT: I have tested the Berserk Equip. It does not work on PC; when placed into storage or any inventory, it has no item icon, just showing a question mark. It has no stats, cannot be worn by any vocation, and if you try to move it from one inventory to any other, the item just disappears. The only things remaining of these items is their item IDs, names, and flavor text.