Holy Swords.
Gremory mentioned it in passing, but there are twelve Holy Swords in total. While each wielder has been revealed differently, we know someone who uses a Holy Sword.
"The Holy Sword my father wields is Ascalon. Long ago, it was the sword a hero blessed by the goddess used to cut off a Black Dragon's head. Our House of Count Aries is the legitimate heir to that hero's bloodline, and the Aries sword style is specifically designed for wielding Ascalon."
"It's a weapon that boasts outstanding power against demons and monsters, especially dragons, dragonkin, and lizardmen. The Count drew Ascalon against that orc named Brug."
"So he beat Brug with Holy Sword hacks."
If he lost to a Holy Sword that killed a dragon, there's nothing to be done about it. While Brug's biggest mistake was stupidly worrying about his weapon breaking, the real culprit was that bitch Forneus for not properly equipping me or Brug. Brug's only crime was being too nice.
