MONSTER HUNTER: WORLD

You'll be able to obtain Rarity 8 Weapons towards the very end of the game's story mode (Hr 13-14 when you can begin fighting elder dragons properly)

Most of these weapons require you to fully upgrade through the tree, and typically required some sort of "Gem". These gems are typically very rare (Nergigante's seeming to be the rarest due to groups drop rates, versus other gems)

However, each weapon has almost the same weapon tree setup with materials, so you don't have to farm outside of what you want to make this process faster.

You do need 5 seperate weapons, this isn't culmulative, however if you have the materials necessary to craft all 5, you can save, craft them, get the achievement, then dashboard so you don't lose all your materials.

A few things to note, I can confirm the Argosy (The Ship you can send out for materials) CAN return with Bird Wyvern Gems, and Wyvern Gems.

Also, carving the tails of elder dragons yield the highest result (even though in most cases is a single chance) to drop a gem. You can also carve them from bodies at a 1% drop rate (in the case of elder dragons) and get them as rewards.

Petting your Poogie (errrr) in town apparently raises your chances at better drop rates as well but that's yet to be confirmed and has been a rumor since the inception of the franchise and is hard to prove. Felyne GoodLuck (might be mis-remembering the skill name) apparently helps too, and there's an armor skill that involves "luck" that also raises chances.

And last note, if farming for Gems, DON'T DO OPTIONAL QUESTS. Do investigations, those gold boxes have a higher chance at giving you gems (in the rewards section), and don't hesitate to post one, drop in, and shoot your flare immediately. People WILL join.

To get this Achievement you must obtain five Rarity 8 weapons. These weapons are the final upgrades for certain weapons and are Orange in color in the Weapon Trees. Getting these is a simple process but very time consuming as you'll need to farm the supplies necessary by hunting the Monsters related to them.

Most of the Rarity 8's require materials from the end game Elder Dragons, so don't bother with this Achievement until you've at least gained the HR needed to take on Elder Dragons (Kirin, Nergigante, Kushala Daora, Teostra, Vaal Hazak, Xeno'Jiiva).

For example here is a Weapon Tree with a Rarity 8 at the end:

Insect Glaive:

1. Bone Rod I - Rarity 1 (Can be bought in the Workshop in town)
2. Go to the Second Fleet Master in the Workshop and choose "Upgrade Equipment"
3. Bone Rod II - Rarity 1 (Requires Monster Bone S x2, and 200 Z (currency of the game like Gold)
4. Pulsar Rod I - Rarity 2 (Requires Tobi-Kadachi Claw x1, Tobi-Kadachi Scale x3, Tobi-Kadachi Pelt x2, and 1000 Z) (Will move from the Bone Weapon Tree to the Tobi-Kadachi Weapon Tree)
5. Pulsar Rod II - Rarity 3 (Requires Tobi-Kadachi Electrode x2, Tobi-Kadachi Claw x3, Electro Sac x2, Coral Crystal x3, and 2000 Z)
6. Garon Rod I - Rarity 4 (Requires Odogaron Claw x2, Odogaron Scale x4, Odogaron Fang x2, and 4000 Z) (Will move from the Tobi-Kadachi Weapon Tree to the Odogaron Weapon Tree)
7. Garon Rod II - Rarity 5 (Requires Quality Bone x5, Odogaron Claw x2, Odogaron Tail x2, Odogaron Plate x1, and 6000 Z)
8. Temptation's Trident - Rarity 6 (Requires Odogaron Claw+ x4, Odogaron Scale+ x8, Odogaron Fang+ x3, Dragonbone Relic x1, and 16000 Z)
9. Vice - Rarity 8 (Requires Teostra Claw+ x2, Odogaron Claw+ x6, Odogaron Fang+ x5, Odogaron Gem x1, and 32000 Z)

In the example above you'll notice that you'll be hopping through a few different Weapon Trees along the way, meaning you'll have to face multiple different monsters to get a weapon to it's final upgrade (also not every weapons final upgrade is Rarity 8!).

You'll notice a few items are not from monsters such as Coral Crystal and Dragonbone Relics, these must be harvested from Mining Outcrops and Bonepiles, Dragonbone Relics being the rarest find from a Bonepile.

Some of the materials have a "+" in them, this means that the monster MUST be High Rank (6 Star Quests or higher) in order to get those materials.

Lastly, some items such as the Gems and Plates are very rare drops from the monsters and will likely requires many runs. Using Odogaron as an example, after killing Odogaron, you get 3 carves and the odds of getting a Plate is less that 10%, you also have a chance to get one at the rewards screen afterwards, but again 10%. Gems are even more rare so you'll have to get lucky here.

All in all the example above is for ONE Rarity 8 weapon and you'll need five, you can repeat the process again or you can get a different Rarity 8 weapon, the choice is yours. Once you get five, the Achievement will unlock.