Its true that, dark Knight are squishier compared to Marauder(with Defiance) or Paladin ( With Shield DEF and lots of Buffs) But its mainly how you play Dark knight, unexperienced Dark knight wont know how or when to use Specific Skills like "Dark Arts" , i had the problem before becouse i didnt know how to Manage using "Dark arts" becouse i thought it was mainly a Huge MP waste for an potency increase like 100-200. but for skills like "Abyssal Drain" Which is same as "Unleash" (black circle thingy) increases Enmity and also Absorbs "Health Points" aswell and they are Both aoe moves. But besides that it should be recommended atleast for Dark knight newcomers to have a little more EQ over nowledge, becouse if you die in 1 Hit , kowning how Dark knight works, hasn't helped either way :P Also hightly recommend to all Dark knight, use Grit, to Grit gud.