I think I changed the place after this guide was made so it's not entirely his fault. He just didn't update this.
Now it's something like this:
Azureus Ring - Chapter 1, Buy: Arnold's Armor Store
Azureus Belt - Chapter 2, Buy: Army Shop
Azureus Shoulders - Chapter 4, Buy: Selling Shade
Azureus Sword - Chapter 5, Buy: Arogaba's Armor Store
Azureus Armor - Chapter 6, Buy: Secret Store
Azureus Relic - Chapter 7, Buy: Richard's Special Store