Malekith explained that when dark elves become the Kurse, no weapon which their enemies posses can stop them. Was he specifically talking about Asgardians? And if so, does this mean that a Kurse's power is "anti-Asgardian"? If this isn't the case, how was Kurse able to deflect the hammer since he wasn't worthy (this assumption is based off the fact that he's a bad guy)? Or was it simply because he had great physical strength?
"You will become darkness, doomed to this existence until it consumes you. Until then, no power our enemies possess can stop you." ―Malekith to Algrim
I think it is related with the Aether. The Kursed Stones were made from the Aether.
In order to become a Kursed, a dark elf must crush a Kursed Stone in his hand and consume Aether's infinite destruction. This is the reason why they are almost invincible. After a while, the power is so overwhelming the Kursed is consumed by death.
Dark elves are of course, stronger than humans but it is not completely related with physical strength. They consume a part of Aether until the infinite destruction consumes them. I think the main reason is the Aether.