Mannequin 3: The Reckoning - S6-E14
Continuity mistake: When the guys tip Rose into the grave, her eyes are open, but as she lands and dirt falls over her face, her eyes are closed. A dead person's eyes don't close on their own. (00:25:20)
Mannequin 3: The Reckoning - S6-E14
Audio problem: In 6.14 "Mannequins 3: The Reckoning", when Dean goes up to talk to Ben, Ben is playing a video game. Dean says something along the lines of "There's no way plants could kill zombies", therefore pointing out that Ben is playing Plants vs. Zombies, but the sounds coming from Ben's gaming system are not from Plants vs. Zombies.
Answer: Angel blades come from angels. It's their angelic magic that makes it special. Therefore, an archangel blade is made magical with the powers of an archangel. They couldn't have just created one or used one, as none of them are archangels.