This will take a long time to do. It took me approximately 2 weeks of 7-8 hours of play a day to get this done.
Couple of notes:
Weapon Devotee MAY BE a trophy based on the first published number of available weapons BEFORE DLC. I'm not really willing to go through the pain of doing is Trophy to confirm. Any future participant who is going through this, feel free to update this or let me know so I can modify this message.
Just as an example: If the base game had 100 weapons and you had completed 3 DLC weapons, then you only have to do 97 weapons in the base game. All this means is, if there were a few DLC weapons that were easier to get, you can go that route over a harder one or a more time consuming one.
Ideally, if you needed to kill Aurogrinder, you could potentially bypass a weapon by building a DLC Weapon instead.
Keep in mind, I am completely UNSURE if the above is valid because the Trophy unlocked when I had 2 Weapons left to complete and the 2 Weapons that took those places were DLC Weapons off of Large Monsters that were not in the base game.
Below are a few notes about items that were hard to find
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Haku Sac is from Ex Umbrapod.
Umbrapod spawn is based on first spawning into map
After 1, 2, 3, 4 and 5 minutes (5 chances per map)
When Large Monster hits 50%
When Large Monster hits 0%
Chapter 6: Dances with Spiders
This has 3 Large Monsters which effectively gives you roughly 12 spawn chances.
Phase 6: Spider Eradication
This only has 1 Large Monster, your rate is about 8 spawn chances.
I highly recommend doing Phase 6: Spider Eradication. It takes about 1 minute to clear. You take the Map spawn chance, 50% and kill chance and a 1 minute chance. So it's about 4 spawn chances in a round and you can queue up again in a matter of seconds.
Chapter 6: Dances with Spiders will take you about 5 Minutes to do so just running it will give you the 12 spawn chances.
Phase 6, at a fast kill speed, you can get up to 20 chances in the same amount of time it takes for you to complete Chapter 6.
For Normal and Ultimate, there is a Special Mission that you can do for Normal Umbrapod and Shadow Souls.
For Ultimate, there is a Free DLC Pack (Mission 1) that will have them available.
Ex is the only one that requires any real time and effort.
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Large Arm Spike is from Nightblade. Blow off his lower arms, do NOT purify them. Let Nightblade regenerate them.
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Hard Icebreaker is from Frostcrawler.
Chapter 13: Age Exploration - Village
Go to the far right zone. It has a Toad and a Crawler. Kill the Crawler and it will spawn a Frostcrawler afterwards. You can do this up to 2 times. This is the most consistent and guaranteed spawn I could find.
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I needed 8 Thundergod Pearls to complete my weapon sets. You can get this off of Ultimate Venom Queen. You MUST destroy her tail which only becomes available AFTER she enrages and drops her Shell. It will not drop under any other circumstance.
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Ex Aurogrinder can be killed via Mission Pack 7 DLC.
Ultimate Aurogrinder is absolutely painful.
The best method is to turn off Auto Save.
Go to Chapter 1 - 7. Kill Manhunter in a matter of seconds.
If you DID NOT get an Emergency Mission:
Save your game manually by the fireplace in your house.
Load up the Emergency Mission and see if it's Aurogrinder (Golden / Green Shiny Terragrinder looking monster). If it is not, go to the Fireplace, DO NOT SAVE, return to main menu, Continue and load up your save. Kill Manhunter and then check the Emergency Mission.
If it is Aurogrinder, Save your game and try to get 2 Treasure Skins off of a kill. Getting 3 is highly rare, but doable (but not time effective). If you're able to get 2 in a kill, you'll have to repeat the process of trying to get another one to spawn.
The only other way to get Aurogrinder to appear is through Special Investigation - Mystery or Earth Attribute. This method is not ideal, there is a significantly higher chance for Soil to drop in place of actual loot. I've killed a total of 7 Ultimate Aurogrinders, 5 of which were through investigation and in place of Treasure Skin, Soil dropped instead.