When wizards are dueling, if they both know how to cast the Killing Curse, then what is the meaning of one being more powerful than the other?
Specifically, we are repeatedly told how powerful Voldemort is. What exactly does this mean? Except for his Horcruxes, he should be no more advantaged in a duel.
PS: This question is not a duplicate. Its essence is that being able to cast a killing curse is the epitome of magical power in duels, and so Voldemort should not have become anybody special.