I posted this on the forums here.
Demon armor: Now also reduces the duration of physical effects on the caster by 30%.
What does this include? Here's a short list:
Deadly throw snare
Garrote (both the silence and the dot)
I'm not too worried about diseases, dots, and rogue poisons, simply because it's possible to cleanse or remove them in some form or fashion. They have counters. The abilities above, however, do not. Most classes can deal with the abilities listed above for various reasons. Warlocks, on the other hand, seem to be designed around the fact that they are best dealt with by having melee sit on top of them the whole fight.
Making fel armor and demon armor undispelable was a good start, but it might be necessary going forward to give demon armor even more passive defense against effects that they really have no other way of getting rid of.
If you're going to design warlock abilities based on the assumption that they are meant to "tank" melee in pvp, then you will probably find that they will need a buff to core abilities and mechanics to help them fulfill this role. This would also make demonic aegis a lot more attractive.
I'd really like to see Demon Armor's armor value scale off of another stat, such as spell power. I.e. static number + 20% of spell power or something along those lines.
I don't think it would be a good idea to scale the armor value off of another defensive stat, such as resilience or stamina. I'd hate to see encouraging locks to be competitive by simply stacking a bunch of defensive stats. It's ultimately less fun in the long run, and fun is what the game is all about.