In The Dracula X Chronicles, when Dracula realizes that he's suffered his most humiliating defeat yet:
Dracula: Completely impossible! Beaten by a little girl?!
There is also the Aria of Sorrow version of Excalibur, The Sword Still in the Stone.
In Portrait of Ruin, there is a cream pie subweapon. Which is already funny in and of itself, but here's the kicker: it has the Darkness elemental property, making it very useful when you fight the Whip's Memory, a projection of Richter Belmont, the last Belmont to wield the Vampire Killer whip. You can beat an extremely powerful vampire hunter by throwing pies at him!
Then there's Jonathan's Badass Boast after beating Death, "I don't need the vampire killer to kick your ass!"
Then there's Order of Ecclesia's Brachyura and Gravedorcus. SHOOUUUURRRGGGGG. As a commenter put it, "mwa haa haa haa. Top this shit, Persona3."