Death Knight armor is unlockable from Artix in Doomwood/Necropolis, after you complete the quest chain. You will need to have unlocked Paladin and Necromancer first, the Death Knight armor is trained in the same way.
DeathKnight Quest
U can't. its only temporary.
You can only unlock the armor during Mogloween/Halloween (and use outside Mogloween with the Armor Closet).
you need to buy it at crysero' orb
You can't yet, but maybe they will issue a deathknight armor in SwordFall coming up. -Atenzia
You don't have to have a certain level. You have to have all the moves on both paladin and necromancer.
You go to Lady Celestia. then go to DragonLord. after that you go to unlock DragonLord armor. then you go on a quest. then you have to beat old man of the mountain then you have the armor. Note: you have to be level 8 or higher to do this
The final act has yet to be released, but it's simply by doing them that you will unlock them all. Buried in the acts is the Frost Moglin Armor.
I played dragonfable for 3 years! Pumpking armor are very easy to have. Do the quest. Is before the pumpking armor. Good luck!
Sadly, the dragonfable team has not come out with the soulweaver armor yet. But I can assure you, it will be out in 2010. For proof, look at the DF design notes.
Hacking
To become a ranger in Dragonfable, head to the SandSea and talk to Zhoom. He has everything you need to do to unlock the armor as well as train it. (TIP: If you don't like constantly having to go back to the area where you unlocked the armor to get it again, buy an armor closet for your house. It keeps track of all of the armors you have and lists what armors you don't.)