The Zodiac Spear is the most powerful weapon in Final Fantasy XII. There are certain treasure chests throughout the world of Ivalice you must not open, in order to obtain this weapon.
The following is a list of four treasure chests you must not open, in order to get the Zodiac Spear in Final Fantasy XII. This Final Fantasy game is only for the Playstation 2 video game system.
Treasure Chest #1 Not To Open
There is a treasure chest outside of Dalan's place. Dalan's place is in lowtown. Do not open this chest.
Treasure Chest #2 Not To Open
Just before you get the Goddess Tear in the palace you sneak inside of, there is a cellar full of chests. In the cellar, do not open the two chests that are in the southeast corner.
Treasure Chest #3 Not To Open
In the confiscatory, the place where all your weapons and armor are given back to you, there are lots of treasure chests here. Do not open any of the treasure chests here. This is actually more than one treasure chest that you don't open, but they are all in one location.
Treasure Chest #4 Not To Open
On the island by Phon Coast there are sixteen treasure chests. The fourth chest in the sixteen should not be opened. For best results, it is advised that you just bypass all of the chests and not get any of them. The chests only contain Gil and not any other treasures.
If you leave all of these chests locked up, you can get the Zodiac spear. You can get the spear in the Necrohol of Nabudis. The Zodiac spear has a 150 attack power to it.