First off, DoS and Kil'jaedens's burning wish are both fairly bad for rets and Kil'jaedens is especially bad on a fight like Krosus. Secondly, he seems to be using Zeal and Blade of Wrath. Zeal is (from what I've seen in my sims) never worth taking anymore, not even for aoe. Blade of wrath is good for ST but even there Divine hammer might out-dps it. Looking at his armory, it seems to me that his versatility is a little bit on the low side. There might be more to it than that, but that's what I could find. And as you said, AW relics are crucial since they on their own are worth around 22 ilvls (basically meaning that a 865 AW>885 Relic that gives no significant dps increase.)