User blog comment:B214/Talk About What You Want! 2/@comment-24409634-20140628103520/@comment-1359322-20140628123210

How?

Take Grendel or Crom Cruach as an example, you think a simple sword would work on them? Even when Issei used a boosted attack clad with Dragon Slayer aura, it had little to no effect, plus for a Holy Sword that can't release large amount of light or Dragon Slayer aura, it's clearly ineffective. Remember Holy Swords aren't like Sacred Gears, the amount of power a Holy Sword possesses is fixed from the start, Ascalon's power isn't good enough for combating powerful Dragon opponents like the Evil Dragons. =