From G+: Duelist (level benefit)

If you want to play a lightly armored lvl 3 fighter, Brawler/Skirmisher is a great combo. But if you want a warrior who wears no armor, skirmisher isn’t so hot a choice—so I made a third option for level 3 warriors:

Duelist
-1s to an opponent’s successful or tied action (Attack, Feint or Maneuver), but only on a roll of 6. Can be used once per conflict, works against all weapons (spears, spells, etc.). Cannot be used if wearing armor heavier than leather.

(Basically, I want to play Samurai Jack…no armor, big-ass sword)

I assume you make an armor roll like normal? It wasn’t exactly clear at first glance what “on a roll of 6” meant.

Yes. On an armor roll of 6 you impose a -1s penalty.

An addendum: You can’t use the Duelist benefit if wearing armor on your torso heavier than leather or if carrying a shield, large sack or wearing a backpack.

What about a helmet?

I’m ambivalent about helmets.

I’d allow a helmet as long at it’s (1) worn with tights and (2) doesn’t cover the Errol Flynn mustache.