I’ll go first. Mine is the instant knockout drug. Like Dexter’s intramuscular injection that causes someone to immediately lose consciousness. Or in the movie Split where there’s the aerosol spray in your face that makes you instantly unconscious. Or pretty much any time someone uses chloroform.
Knights getting stabbed with swords through plate armor.
We’re re-watching GoT and were at the Brienne/Jaime fight on the bridge, and I was just yelling at the screen. He’s in rags and she’s in plate, both wielding swords, he doesn’t have a snowballs’ chance in hell if she protects her head and just tackles him. That’s what the fucking armor is for! Coincidentally that also would be way more likely to achieve her goal to subdue but not hurt him.
IIRC, neither was wearing armor in the book, but it’s been a while so I may be wrong.