Defiant gear was introduced some time during Secrets of Faydwer. It's gear that drops all around the world from mobs of every type. The higher level the mob, the higher level the Defiant gear it will drop. Due to how common Defiant gear is to find it doesn't sell that well in the Bazaar.
Below is a list of all the tiers of defiant gear.
Crude Defiant Gear (Recommended level of 10. No required level.)
Simple Defiant Gear (Required level of 5. Recommended level of 20.)
Rough Defiant Gear (Required level of 15. Recommended level of 30.)
Ornate Defiant Gear (Required level of 26. Recommended level of 40.)
Flawed Defiant Gear (Required level of 37. Recommended level of 50.)
Intricate Defiant Gear (Required level of 48. Recommended level of 60.)
Elaborate Defiant Gear (Required level of 59. Recommended level of 70.)
Elegant Defiant Gear (Required level of 70. Recommended level of 80.)
Q: What expansion do I need to get this gear?
A: None, you can get it and equip it with any expansion.
Q: How expensive is this gear in the bazaar?
A: Usually less then 100pp for the weapons and 250-2500pp for each piece of gear.
Q: How common is this gear?
A: By level 50 you'll probably see two dozen pieces drop.