Dark Armor was a set that definitely was made better with IOs. I think you absolutely would want the Numina and Miracle uniques in Health, and Stamina 3 slotted including the Performance Shifter +end proc. DA demands a ton of recovery/endurance. Come to think of it, you'd likely also want to prioritize any of the accolades that increase your base END. Getting in a little extra end reduction or recovery via frankenslotting, set bonuses, etc will go a long way to making a DA character playable.
That said, there's one single IO that is pretty much gamechanging for Dark Armor: Theft of Essence chance for +endurance proc placed in Dark Regeneration. If you fire it off in a crowd, each foe gives you a chance to recover endurance. It turns a very endurance heavy self-heal into a blue inspiration. It is *that* good. But in the early game, until you resolve endurance issues, you might find yourself picking and choosing which auras you'll run based on the enemies you fight . . . it is hard to keep them all up without support. Another key IO to get is a Knockback Resist IO . . . a melee character with no KB resist is a pain to play. Get at least 1, and perhaps 2.
I'll second what Thunder Glove said about DA being kind of non-traditional with a couple of amplifications. Many of DA's powers can work at cross purposes with each other. For example, the damage aura isn't great to run at lower levels because you don't have much damage mitigation to handle all the agro. The fear PBAOE works at cross purposes with the damage aura because the damage wakes them up from fear. The stun aura causes foes to wander out of the damage aura range. You have to be tactical about what power you use and when. On the other hand, you can use the variety of effects to handle a wider range of situations . . . I love the idea of using the KB-KD proc in the damage aura!
You will have resistance to everything, but Energy Resistance is pretty low in DA so keep that in mind when you are at higher levels and many enemy groups have powerful energy attacks. You have a relatively weak DEF power, but I find that stacking other DEF powers (if you can stand the endurance hit) is worthwhile even if you aren't softcapped to anything. You'll want Tough anyway for the extra smashing/toughness resistance, so taking Weave is a no-brainer. Combat Jumping would add a touch more DEF (and a place to stow another LOTG +Recharge). Getting softcapped would probably be incredibly expensive and require sacrifices in other areas of your build, but purple inspirations are a thing, and considering you have a -To-Hit aura, extra DEF adds synergy.
Looking at Savage Melee, it brings a couple of things to the table. A 2nd self heal seems nice and would give you some staying power if you didn't have a bunch of foes in melee range. 2 extra PBAOEs and a cone attack are decent, and the KD component of Viscous Slash seems worthwhile. I could see a couple of different angles with the ancillary power pools; Mu for the extra AOE goodness or Soul for the great toolbox. This is just a guess, but Darkest Night with its -damage and -to-hit could be another great layer of mitigation, gloom is certainly a great single-target power for a brute, and you could still get some targeted AOE fun.
I could see Savage Melee/Dark Armor as being very fun to play if you enjoy tactical decisions and getting under the hood with IOs. Straight out of the box on SOs it isn't going to be good, but you have so many options to customize it, it can be very powerful. In teams any support you get via buffs and debuffs will shine all the more since you are so versatile.
