Nethicite

Nethicite
In the worlf of Ivalice in Final Fantasy XII Nethicite is the most powerful source of magical energy. There are two types of Nethicite Deifacted and Manufacted nethicite.

Deifacted nethicite
(((Spoiler))) Deifacted nethicite was created by the Occurians in the form of the Sun Cryst. It has a large amount of magical energy stored within it. The Occurians chose to give Nethicite first to the Garif but they would not use it to impact the world's events, so it was taken from them. King Raithwall was then selected. He was given a sword that could cleave pieces from the Sun Cryst so that he could wield the power of Nethicite in his hands. He severed three pieces, the Dawn Shard, the Dusk Shard and the Midlight Shard. Each of these pieces held so much power that it guaranteed his victory in battles and his legend. He also possessed a weapon capable of destroying the Nethicite, The Sword of Kings.

The three pieces of Nethicite had enough power to destroy cities and fleets, but could only be used once before needing to recharge slowly over hundreds of years. Judge Zecht used the Midlight shard to destroy nabrudia. Judge Ghis used the Dusk Shard and accidentally destroyed himself and the entire 8th fleet.

The Occurians chose Ashe to be the next Dynast King and provided her the treaty blade in order to carve more Nethicite shards to grant her the power to destroy her enemies and rule.

Manufacted Nethicite
(((spoiler))) Manufacted Nethicite was created by Dr. Cidolphus under direction from rogue Occurian Venat. The Nethicite seems to have been created in the Draklor Labs, but produced in the Lhusu Mines, Where Lord Larsa was searching for more information about it. Initially it appears that manufacted Nethicite has the ability to disrupt or cancel magics directed at the wielder. It is later revealed that if someone is to become bonded with the Manufacted Nethicite, they can increase their strength and magical abilities immensely. Judge Bergan, Dr. Cid, Judge Zargabard, And Vayne Solidor are all known to have done this. Judge Ghis regarded Manufacted nethicite as a weak bauble next to true Deifacted nethicite.

nethicite related artifacts
There are 2 artifacts in the game that hold any power over Nethicite:

The Sword of Kings has the ability to destroy Nethicite. This Artifact was hidden in the Stillshrine of Miriam by Raithwall the Dynast King. It is possible to infer that Venat presented this blade to Raithwall.

The Treaty Blade This blade has the ability to carve pieces of nethicite from the Sun Cryst, and presumably to cut smaller chunks from other Deifacted nethicite, though it is never shown or mentioned to have this ability.

Additionally, there are three pieces of Deifacted Nethicite. Each piece is said to be able to reveal a true descendant of Raithwall the Dynast King:

The Dawn Shard is hidden in the castle in Rabanastre.

The Dusk Shard is hidden in Raithwall's tomb. This piece was found and subsequently used, destroying the Airship Leviathan and the entire 8th fleet.

The Midlight Shard was used to destroy Nabrudia during the war.