Each of the game’s character has a very high-powered weapon that they can obtain called a “Celestial Weapon”. Finding each of these Celestial Weapons is fairly straightforward.
However, when you first receive these weapons, they only come with one ability called 
No AP, which makes them practically useless. You must obtain the 
Celestial Mirror in order to begin powering up each of these weapons.
Make your way to the Calm Lands and talk to the Chocobo Trainer in the northwest corner of the map. She may be wandering around in other places on the map if you don’t find her there. She sometimes hangs out directly in front of the camp.
You must complete the Chocobo training side quests if you have not already. This involves completing each of the Chocobo mini-games listed on the following page:
Talk to the Chocobo Trainer once you have completed the training side-quest and choose to ride a Chocobo. Head over to Remiem Temple (you need to be on a Chocobo to reach it). Go to the southeast portion of the Calm Lands and look for the feather on the ground shown in the screenshot below:
Enter the temple area on foot and follow the pathway to the left of the Save Sphere at the entrance. Find the Sphere on the ground next to the Chocobo and examine it.
The dialogue that appears while examining the Sphere will explain that “you have been accepted as a true rider.” This means that you can now ride Chocobos in this area to compete in a small mini-game.
Run over to the Chocobo on the opposite side of the temple (to the right of the Save Sphere). Press the 
Button near the Chocobo and choose to ride it.
The object of the game is to race to the center of the temple. For the purposes of obtaining the Celestial Mirror you can ignore the colored posts and the treasure chests.
Just race into the center (middle) of the temple as quick as you can in order to win. All of the pathways converge at the pedestal in the center; just make sure to dodge pathways with treasure chests at the end or those that lead to dead ends.
Your prize for winning is the Cloudy Mirror which you must now restore to turn it into the Celestial Mirror.
Note: You have to have defeated Seymour Natus after traveling through the Via Purifico (click on the link to view that section of the walkthrough) in order to complete this step.
Travel back to the entrance of Macalania Woods. You can either walk there or use the Airship to travel to Lake Macalania and then backtrack from there. Use the Save Sphere at Remiem Temple to board the Airship and then warp down to Lake Macalania as this is the quickest route.
Note that if this is your first time returning to Lake Macalania there is a treasure chest behind where Clasko was previously standing that contains 4,000 gil.
This is the area where Auron carved a pathway through the woods just before you fought the Spherimorph. Travel southeast from here to find a new secret pathway. It should lead you to the sparkling walkway shown in the screenshot below. Use it to quickly travel to the entrance (without encountering fiends).
This pathway will lead you on a shortcut that will speed you through the entrance. The pathway is technically straight right now as the only intersection is blocked off by a lady that will tell you about when she used to pass through here. Continue along the pathway until you reach the entrance with the Save Sphere.
There is a woman and a small child at the entrance. Speak to the woman and she will explain to you that her husband is missing. Speak to the child as well.
Take the pathway to the right of the woman and the child.
Go directly right one more time and then north at the next screen.
The husband is the one on the right. Speak to him and answer him with “They were waiting over there.” Now go back and speak to the woman at the entrance to Macalania Woods again twice. She will now mention that her son went off into the woods before the husband came.
Travel along the sparkling walkway again until you reach the ‘T’ intersection on the second screen (where the woman was standing previously) and take the pathway heading north. The missing son is at the end of the pathway.
Speak to the son and you will be presented with an option to “Use the Cloudy Mirror?”. Select “Yes” to have Tidus hold up the Cloudy Mirror and turn it into the Celestial Mirror. The son will now return to his parents.
In order to power up a Celestial Weapon using a Crest or a Sigil you will need to return to this spot while in possession of the correct items/weapons and examine the large orb shown in the screenshot below in order to combine the items and power up the Celestial Weapons.
Use the links below to return to the Celestial Weapons listing, which contains details on where to find each of the Crests and the Sigils for the weapons, or the use the link below that to return to the “End Game Side Quests” strategy guide section:
