A new tank stance to fit Dark Knight better

[Ceodore]

It is called an Advanced job for a reason. Also, you can choose not to use Darkside, thus negating the HP penalty entirely if you want to just be a strong tank. Thus you don't need the sacrifice unless you want more damage.

It is not required to tank though, it would be a choice.

Choice, but ultimately out of the developer's intended theme, and a requirement because parties want all the damage they can get. Further, you don't take into account that Grit already triggers a Global Cooldown like Shield and Sword Oath, as well as breaks combos. So is the plan to also have it up during OT DPS phases, draining your MP AND HP while also ripping agro from your main tank because there's no reduction in your damage while Grit is up? That's pretty stupid. So drop Grit during OT phases? Well, gonna suck if you have to quickly return to being MT, and since it triggers a global cooldown, can't switch at the drop of the hat either. You say plan and anticipate things, but the global cooldown in this game is 2.5 second. That's a lot of time for a tank swap that quite likely just went wrong and since DRK doesn't have any skills that generate additional enmity that are off the GCD like Circle of Scorn, you're looking at losing agro again right away. It isn't like Defiance, which can just be thrown up then immediately followed by a Butcher's Block.