You would not be able to open that door until Final Fantasy chapter 15. Notably, this is the second dungeon area that you will find behind the sealed door in the main dungeon. Notably, we are talking about the dungeon that you visit in chapter 7 with Aranea, but you’ll have to wait until Chapter 15 to actually get it. You can find The Balmung Final Fantasy weapon in the Steyliff Grove dungeon. It is an end game sword for FF15 that provides stunning attack stat, plus bonus damage for each hit based on how low your MP is. The Balmung is yet another impressive weapons that comes handy a lot in FF15.
