While the Dark Knight job has traditionally been a DPS (damage dealing) affair, Yoshi P and his development team decided to change that up a bit for Final Fantasy 14: Heavensward. In the first expansion for Final Fantasy 14, the Dark Knight is a tanking job. In fact, there was a glitch that allowed it to inflict a considerable amount of damage that was quickly patched out of the game before players could get much use out of it.
Final Fantasy 11 players may be wondering why the Dark Knight's doesn't have a scythe. This time around Dark Knights use a great sword, but if you're looking for a job that uses a scythe, the Botanist's secondary weapon is a scythe. While it probably won't fill the void left by the Final Fantasy 11 version of Dark Knight, at least you can find some nice harvesting points. All jokes aside, let's take a closer look at the Dark Knight in Final Fantasy 14.
How to Unlock Dark Knight
Once you have completed the main story for A Realm Reborn (and presumably have at least one job at level 30 or higher), head to Ishgard and speak with the Ishgardian Citizen at (13,8) to begin the Dark Knight job quest. After a few cut scenes and a small amount of traveling around you will gain access to the Dark Knight job, starting at level 30. As soon as the quest completes you can begin the next Dark Knight job quest to obtain the Darkside ability. While you don't need this to start leveling Dark Knight, it's extremely helpful, so complete the second quest to get it out of the way now.
While Dark Knight is a unique tanking class, it does share quite a bit with Paladin and Warrior. Most notably, Dark Knight has two stances that it can use depending on the situation at hand. The first stance is Grit, which is very similar to the Paladin stance of Shield Oath. It generates enmity while reducing damage taken by 20 percent. However, it also reduces the damage output of the Dark Knight by 20 percent. This is your primary tanking stance and should be used at the start of a battle anytime you're the main tank.
The second stance for the Dark Knight is Darkside. While Darkside is active the Dark Knight inflicts 15 percent more damage, but their MP slowly drains in the process. Unlike the Paladin and Warrior stances, Dark Knights can activate Darkside while Grit is active. As long as the Dark Knight has MP to burn, that means the damage output of a Dark Knight with both Grit and Darkside activate is only cut by five percent (instead of the normal 20 percent reduction from Grit).
How to Tank
While Warrior relies heavily on TP and Paladin uses a combination of TP and MP, the Dark Knight tanks almost exclusively with MP. If you run out of MP you lose a lot of your tools and general versatility as a Dark Knight, so it's important to keep an eye on your MP. If you have a Bard, it may be a good idea to request Mage's Ballad when your MP starts to get low. Unfortunately, you won't be able to rely on most Bards to do this on their own.
When you first engage an enemy while tanking as Dark Knight, you should be in the Grit stance. Once you've established hate with your Hard Slash > Spinning Slash > Power Slash combo you can activate Darkside to increase your damage output. Since many of your attacks drain MP while in Darkside, in addition to the stance draining MP slowly, it's important to use the Hard Slash > Syphon Strike > Souleater combo to replenish some of your lost MP.
A Dark Knight should use Unleash to generate enmity on multiple enemies at once. Think of this like you would Flash for a Paladin or Overpower for a Warrior. You can also use Scourge, which is the Dark Knight's damage over time (DoT) attack and also generates a bit of enmity. It doesn't generate as much enmity as Unleash, but it still adds to your enmity and helps out in the long run. Just like the other tanks, Dark Knight can stun enemies with the Low Blow ability.