Yep, the helmet was a Magic Feather.

To pull this off in a game, you can actually give a PC some item and hint strongly that it's a +3 Dragonslayer Sword or a Belt of Charisma or what-have-you. Then put them in a fight against a dragon, or an opportunity to talk back to a king with bravado.

Then enjoy as the dragon slaughters them or the king slaps them in chains. Ha ha ha!!

Oh wait... it wasn't supposed to work like that.

Transcript

Obi-Wan: Right. I'm off to get the Orb, then.
Obi-Wan: Remember, Luke, be careful with your laser sword.
Luke: Just give me that helmet, I'll be fine.
Obi-Wan: No, actually, the plasma goes straight through those things.
Luke: But you said...
Obi-Wan: That was just to give you confidence. The sword will cut through anything.
Luke: So the helmet...?
Obi-Wan: Warm. Butter. {walks away}