Quest look like below:
1. At prontera, talk to Armor Merchant【乔亚】.
2. Select the 1st option to access the armor shop.
3. If you don’t see the required armor【铁盾】, select the all job at the top of the shop interface to show all the available armor.
4. Select and buy the required armor.
5. Talk back to same NPC, Armor Merchant【乔亚】to complete the quest.