I'm trying to figure out that since dragon slayers either learned their magic from dragons, implanted lacima, or both, how have they not been able to kill the dragons? I mean Natsu is one of the strongest DS, with Laxus definitely surpassing him, and none of them were able to inflict much harm to the dragons. So i'm thinking is their magic flawed or weakened? Because I remember in some chapter it saying that the ancient dragon slayers were able to kill their dragons. And Acknologia killed countless ones and bathed in their blood. How'd he manage to do such a feat if his original magic power was comparable to Natsu or some other DS who isn't even able to kill a dragon. What are some thoughts of this.