As long as he holds the Sacred Ring of Paladia, he can wreak the same sort of havoc on any city in the world as he did upon Olderion.
The sacred vessel of Paladia (パラデイアの神器, Paradeia no Jingi?), also called the sacred ring of Paladia, is a legendary artifact from Final Fantasy Brave Exvius. An ancient relic from the world of Paladia, it is said to multiply magical power many times over.
Of unknown origins, the vessel was a sacred relic in Paladia but it ended up in the world of Lapis in the conclusion of the Paladian civil war between Aldore and Hess 700 years ago. In the final battle it was used to badly injure Dark Fina, called the "Demon of Hess", who was the last sage of Hess who had to be sealed in a crystal.
The vessel's location and usage is unknown for the following centuries (though it became known to the inhabitants of Lapis, as Nichol was able to recognize it), but it ended up in the continent of Grandshelt.
About 20 years ago, Raegen sought the sacred vessel to restore the power and memories of his adoptive brother, Rowen, who had lost them due to being sealed in a crystal during the war. Raegen joined the Grandshelt Royal Guard in order to gather clues about the vessel and eventually found it inside an enraged ochu in Latius Woods. He gave Rowen the sacred vessel, but Rowen threw the relic to the ground and refused to use it. Rowen thanked Raegen for what he had done, but he was happy as farmer, with his wife Yona and their baby son Lasswell. Without a use for it, Raegen presumably hid the sacred vessel in the Lanzelt Ruins.
After a long search and the attack on Grandshelt Castle, Veritas of the Dark finds the sacred vessel at the ruins. He breaks the statue where it is hidden and takes the sacred vessel. Rain, Fina and Lasswell, who followed his trail since Grandport, confront him but he easily defeats them and leaves with the relic.
Shortly after the Invincible takes to the skies, Veritas of the Waters asks for the sacred vessel, which she needs to enact her plan to destroy the Water Crystal, which is protected by a barrier erected by the Water Priestess Luka. Waterlord uses the sacred vessel to injure the water god Leviathan and pollute the waters of Lake Dorr, thus negating the waters' protection on Aquapolis Olderion. As planned, the Water Priestess is lured to the lake, but Waterlord is unsuccessful in her attempt to kill the priestess is escorted by Rain's party. As she flees, Luka descends to the lake to purify the waters and heal Leviathan, and gives Fina access to the Water Crystal.
The morning after, Waterlord used the sacred vessel to flood the Aquapolis and taunts the party. In the struggle at the market, Fina touches the sacred vessel and awakens her original persona, Dark Fina. Waterlord flees, having correctly assumed they will use the power of the Water Crystal to save the Aquapolis. Dark Fina, however, can track her location by sensing the sacred ring and they pursue her. The party fights Waterlord aboard her ghost ship and she is defeated, and drops the vessel accidentally. Rain takes it but the sacred vessel forcibly awakens the power of the blood of Aldore within him. Waterlord seemingly disappears (she enters Elle's shadow) and Dark Fina keeps the sacred vessel for herself.
They make their way to the Water Shrine. There, Elle is killed and Waterlord shatters the crystal. However, it is still brimming with Elle's power and Fina uses its power, that of the sacred vessel, and her own to save the Aquapolis and Rain, but she is forced to rest and switches places with Fina for the moment. The sacred vessel remains in her possession from then onwards.
Dark Fina uses the relic again after the Dark Crystal, the last one remaining, is destroyed in Pharm and Lapis begins to lose stability as the seal on the land has been fully broken. She initially accompanies Rain and the others as they climb the Land of the Crystals to stop Sol from opening the dimensional gate, but she later leaves the party and goes to the Earth Shrine. Dark Fina uses the power of the sacred vessel and turns herself into a new Earth Crystal. She thus seals the land once again and enables Fina to carry on existing. Presumably, the sacred vessel either remains with her or can no longer be used, as it hasn't been seen since.
The term Jingi (神器?) is used for the Imperial Regalia of Japan, or Three Sacred Treasures of Japan, legendary items used during the enthronement ceremony in Japan. They consist of the sword Kusanagi, the mirror Yata no Kagami and the jewel Yasakani no Magatama. The regalia represent the three primary virtues: valor, wisdom, and benevolence.
Palladia is the plural form of palladium. Palladium is Latin for "safeguard".