https://bdocodex.com/th/theme/6195/
выполнять все квесты у персонажей, побочные

10 https://ibb.co/GCN7qvt
9 https://ibb.co/VWnZz6f
8 https://ibb.co/kqYqjwT
7 https://ibb.co/YQqbvQx
6 https://ibb.co/2stHTRH
5 https://ibb.co/rcP40bd
4 https://ibb.co/vmg1wJQ
3 https://ibb.co/t2VTbWZ
2 https://ibb.co/ymCK4Y4
1 https://ibb.co/gyQkWvm

Go to Grandus(Armor Vendor) and get quest : Faulty Shield.

Chain of quests:
1. Faulty Shield
2. One-Day Workshop Experience
3. Check Out Iron Ore
4. Magnetite in Storage
5. Workshop Forge

After completing #5, the knowledge "Refining a Steel Sword" will be available.

Continue the quest for the next knowledge.
6. Workshop Refining Technique

After completing #6, the knowledge "Calpheon Workshop Refining Method" will be available.

Continue the quest for the next knowledge.
7. Finished Goods Delivery
8. Apprentice Manager Certificate

After completing #8, the knowledge "Calpheon Workshop Apprentice Recruitment" will be available.