Shout outs to Jinyi Kaz for telling me about this method and Shout outs to LetsGetPitted for discovering this. Alrighty I think that this method is the best of the best because the chest spawns 100% of the time with this method so I can say that it truly guarantees you the chest this time as for the Weapon it should too as long as you follow these instructions in the video or this description. This method is a true RNG manipulator.
Sources of this video's method: https://www.youtube.com/watch?v=1VpFs1O8s9I&t=781s
https://www.youtube.com/watch?v=zAHrtUb_wY0
STEPS:
1. Start a new game
2. As Reks skip all mob battles except the boss fight and the fight when Basch leaves you.
3. Go back and save your game. (This file will be your manipulator. You can copy the config settings for this file if you want to. Just in case if you don't get it to work. Each new game you make is different depending on the settings you start with so be careful. Most settings do work but sometimes it might not.)
4. To the get diamond armlet just go to trial mode with any file that has the Aerodome available and get the chest in Trial 1 as shown in the video and kill all the mobs after you get the chest for an autosave to save your diamond armlet. (Earliest point in the game for the aerodome is after the Mimic Queen fight. If it is your first flight don't worry you will still be able to get this to work as well as all subsequent flights too.)
5. Now quit to the title and load that autosave with the newly acquired diamond armlet and go to the Aerodome with your Diamond Armlet equipped on Vaan. (He does not have to be in a party or be the person in the party as long he is equipped with the diamond armlet.)
6. Take the flight from Rabanastre to Nalbina.
7. Make the autosave on the airdeck and quit the game.
8. Restart the game and load the file with Reks that you just recently made.
9. Now start using cure.
10. As your using cure, you want to see these two sequence of healing numbers which are 88, 97, 90 or 97, 94, 95. (Due to different models of the PS4 or Versions of the games it could place you somewhere far on the RNG position for these sequences to show up. So the curing may take some time. Use the crystal to restore your MP once you run out. It will not change your RNG position.)
11. If one of these showed up exactly in this sequence stop exactly at that final number from any of the two sequences of numbers.
12. Now quit to the title and load up your autosave with Vaan on the Airdeck. (I repeat do not restart the game. If you do you will have to do the curing part again to get it to work.)
13. You can now go up the stairs and check for the chest. ( If it doesn't spawn that means that one of the sequences did not work for you. So try the other one to see if it works for you by quitting the game and restarting then loading back in with your Reks save file at step 8.)
14. Once the chest spawns and depending on which sequence of numbers that worked for you to get it to spawn. You will have to use one of these ending methods to the weapon to spawn from the chest.
15a. For the sequence of 88, 97, 90, you will have to pay attention to the man that walks up and down the stairs. As you are walking to the chest he should be walking up to the top of the stairs as the first time. On the fourth time he walks up to the top of the stairs that is when you press X for the Seitengrat. The timing is very easy to get so if you get him while he is moving to the left, you will still get it. You can speed up this process of him walking up and down the stairs until the fourth time.
15b. For the sequence 97, 94, 95, you want to pay attention to the kid who will be by the rails when you get up to the chest. You want to time it when he comes back to the rails again and then Press X when he stops. The timing is also easy to get because he stops there for awhile.
16. Go back to in and out of the cabin for the autosave to save the weapon to be in your inventory and quit the game again and repeat from step 8 until you get as many as you want.
So yea this is pretty much the method to getting it 100% spawn for the chest and 100% for the weapon as well.
If this method does not work for you then I have now clue how to help you.
So comment and tell me that you got it.
To watch me live, go to twitch.tv/nozomu10.
If you any of guys wanna support the channel by donating, donate at https://twitch.streamlabs.com/nozomu10.
You are not obligated to but you can if you really feel if you must
