I could be completely wrong with this pairing. Nor do I know who to contact to confirm it. But I may have figured out which purple armor you should equip every class with. All can be obtained mostly through Raids and Contributions.

Melee: Light Knight (Berserker)
Ranger (Mage Slayer)
Heavy Warrior (Stalwart Bastion)

Range: Gunsman(Charge Stopper)
Assassin (Murderous Assassin)
Archer(Stalwart Hunter)

Magic: Clergy(Archer's Bane)
Scholar(Bloodmancer)
Sorcerer (Stalwart Bloodmage)

Again, I might be wrong. But I hope it helps.


Footnote: I looked over both Bladed and Dragoon Sets. Both sets are purple armor too. But both are more powerful than the armor I listed above. In their perspective Types, any Class can wear them; specific free. You can obtain the Bladed Set through Raid as well. Dragoon Set, on the other hand, can only be obtained through Gacha.