One of the services you can access inside the Pocket Castle is Papi’s Smithy. A total of four tiers of equipment can be bought here: Iron, Golden, Mithril and Crystal. She starts out with only Iron Weapons and Armour, the higher tiers can be unlocked through this quest.
Similarly to Vanilla’s Inventory, Papi’s Stock gets reset when you start a New Game+. However, you don’t need to go through the process of recruiting her again, unlike the Vampire Girl.
The only prerequisite of this quest is Papi being a Companion. She needs to be in the party when you speak with the Blacksmiths.
- Get the Gold Ore from Midas Abandoned Mine.
- Talk to the Midas Village Blacksmith, he’ll agree to teach your Dragon in exchange for a Stone of Chaos.
- Go get the Stone of Chaos (they’re dropped by monsters from the first Tartarus).
- Talk to the Gold Smith again and give him the Stone (unlocks Golden equipment, gives Papi the blacksmith Achievement)
- Advance the main quest to the point where you fight Page 65537.
- After defeating her go talk to the Pope.
- Go to the Amos Mountains and get the Mithril Ore.
- Talk to the San Ilia Blacksmith, who’ll say that you need strong faith to forge Mithril.
- Recruit Sofia, Christie or Rosary (Sister Lamia, Succubus Nun and Slug Nun respectively).
- Get one of them to 10 affection and talk to them in the Pocket Castle to get the Proof of Faith.
- Talk to the Mithril Smith again and show him your Proof (unlocks Mithril equipment).
- Go pay a visit to the Lizard Boss in the Saloon Mine, after defeating her you can take the Crystal behind her throne.
- Go to Saloon and take a look at the Blacksmith’s wares.
- Talk to her again and she’ll agree to teach Papi in exchange for Star Sand.
- Go get it from one of the chests at Saloon Hill.
- Deliver the Sand to the Crystal Smith (unlocks Crystal equipment, gives First class blacksmith Achievement).
- Advance the main quest until you prove yourself in the Coliseum for Grand Noah Queen.
- Get the Dragon Bone Ore from the cave south of Grand Noah.
- Give it to the Grand Noah Blacksmith.
- Get the Fighter's Badge from the Coliseum.
- Show it to Grand Noah Blacksmith (unlocks Dragon Bone equipment).
- Get the Orichalcum Ore from the cave west of Gold Port.
- Give it to the Dragon Girl in Gold Port Smith.
- Get the Dragon Forge Hammer from the Northern Undersea Temple.
- Show it to the Dragon Blacksmith in Gold Port (unlocks Orichalcum equipment).
- Get the Rainbow Ore from The World Tree.
- Talk to the Elf blacksmith on Fairy's Island (unlocks Rainbow equipment) after resolving the Queen Elf situation. (Not sure if any pre-reqs are needed for this scene, it just automatically completed for me).