Each set of cursed gear has a downside, something that takes away from your character. most of the time it's not very important to getting your job done.
Adaman = MND/INT Shura = -HP Hecatomb = +slow% Koenig = -STR -DEX Crimson = makes you susceptible to "dragon killer"
Don't use these with weapon skills as a DRK. Spinning slash/groundstrike/spiral hell all have INT as a modifier and you'll see a decrease in damage from the INT penalty. Macro in the AFv2 gloves or pallas/alkynous (sp?)braclets instead.