It's done by a resource collection(check your "living" tab in character menu)
A request of Wan Daye
Man Dae Ya’s costume (6)
- availbale at FC4 <---------------- this means you can make the 400 def set at level FC 4
Dragon-Embroidered/Lotus Jacket
Dragon-Embroidered/Lotus Pants
6 golden threads high level
reward: Man Dae Ya’s costume (6) (400 def, 100 hp, 100 ve)
Man Dae Ya’s costume (7)
- available at GL4
Violet Silk /Red Jade Silk Jacket
Violet Silk/Red Jade Silk Pants
13 golden thread high level
reward: Man Dae Ya’s costume (7) (500 def, 150 hp, 150 ve)
Man Dae Ya’s costume (8 )
- available at LM4
- ?
- ?
18 golden thread high level
reward: Man Dae Ya’s costume (8 ) (600 def, 200 hp, 200 ve)
Source: