RPGMemes

I remember a one-shot that had a twist like that - followed by the twist of the recently disarmed fighter removing his armored gauntlets, pointing at the traitor, and casting the system's equivalent of Magic Missile. As he pulled his magic sheet out of his pocket he explained that he'd just been a misleadingly strong and well-armored wizard all along but hadn't told anyone but the GM.

That was a fun little moment.