If you collect the five armaments after the world is fused, then return to Isapolis you'll unlock Vai.
Unlock Secret Character Doll
To unlock Doll you must get Nephi after visiting the entrance to Isopolis. Once done, go back to the Corridor of Clouds and go to the entrance of Abraxus' Tower. Rather than entering the tower, go to the right and examine the door you see there for Nephi to unlock. Afterwards locate a purple person and examine him. A cutscene will comence and you will gain Doll in your party.
Unlock Sigil Equipment
After The Forbidden takes control of Vai and partially fuses Artania with the Black Rift, you can obtain the Sigil equipment (previously the Armaments).
||How to Unlock
||Go to the Desert of Black Sand located east of Polamaze. Make your way to the dungeon located in the south-east and defeat the boss to obtain the Arml
||go to the Arena (where Xanadu previously was) and enter the Team Battle; make it up to the 9th battle, then opt out.
||Visit Tradefair the quest for this piece. The Blade can then be obtained by defeating the boss of Draken Mansion.
||buy in a shop right next to the clothes shop in Tradefair; it costs 100,000 GP and is the only item for sale.
||beat the boss on the bridge leading to Tradefair