I'm pretty sure there is no way you can get Dragonlord or Defender if you do not have a verified upgraded DF account.
Also, I found this guide on the BattleOn forums:
Class Type: Melee
Notes/How to use: Defender is a sort of "Tank". It has extremely high endurance and many skills are defensive. When fighting physically, keep spamming Crushing Sweep every time it cools down. When your HP hits around the 3/4, you can go ahead and start using Defender's Oath. If your fighting a monster, use Retaliation when your HP is at about 1/4 of your maximum. This attack will get extremely powerful the longer you wait and should be used as the finishing move.
Notes/How to use: This is how Defender class should be used. Having every enhancement put as fighter, and having a passive skill that adds 15% additional HP from your original total amount, it's a tank. A damage absorbing tank. This should be used mostly when fighting in a group. As with the offensive, always have Crushing Sweep active and use Defenders's Oath when you feel necessary. When an ally is being targeted, you can use Commanding Strike to make the monster focus only on you. You could use Defender's Oath here to help out the aforementioned ally at this point. When you feel that the monster has dealt a lot of damage to you over the time of battle, activate Retaliation.
(Credit goes to Trog)