... i am desperately trying to understand. the only native defense Dark has is a minimal amount in Cloak of Darkness. But.. let us put aside that question.
The reason I dislike Defense on Dark is two-fold. 1) Defense, while the premier Protection in our game, is a 1 trick pony. pass/fail. 2) Dark has no Defense Debuff Resistance.
Here is my "boilerplate" opinion on Dark Armor Brutes... I think Dark Dark reaches its ultimate on the Brute. It is easier to be survivable on the Tank but achievable on the Brute. Like almost same survivability. Then there is the fact that the Dark Armor “Tanks” really poorly. Not in survivability, but in design. Part of the survivability of Dark is the stealth field. In survivability Def>Res>Heal. Dark literally stands this on its head. No defense or nearly none. No defenses debuff resistance so worthless to build. Instead Stealth, two toggles that do crowd control, massive to hit debuffs, and the best heal in the game. But that stealth, non suppressed stealth. Bad from a Tanker perspective. Great on a Brute
You have to PLAY Dark Armor. It is not Stone or Invulnerability. You are a Bishop on the Chess Board. On your color (Black, of course) you F-ing RULE. USE the stealth, it does not suppress. Be aware of how your powers are affecting the mobs. Are they being feared? Stunned? then they are NOT attacking you! DEFENSE!!!!!!! Play each fight to win, be engaged, plan ahead. Dark is not a stupid persons armor. I know you are not stupid, but many gamers want to "chill baby, I'm on my unstoppable Brute!" and.... tragedies happen. You have to work your butt to utilize the entire set to it's fullest.
Defense is great! Without DDR less so. At the cost of ANYTHING that might strengthen the Resists, Fear Cloak, Stun Cloak, Heal of Dark? Just cheating yourself out of more Dark so you can play like Invul. (Then they strip your Def away) You want Def? It will be there on Leagues with Destiny Barrier (Which you should get!) Sacrificing good slots and build options for a few points... I could say something about that. Um, wait. I just did...