When I was in the States I remember reading B stories and seeing the word "moxie" quite a few times. At that time I had a very BAD English/Spanish dictionary and that word was nowhere to be found, so I just asked a couple of friends there. Nobody knew what the heck moxie meant. Finally, somebody in the Special Collections Department came up with a good dictionary and explained the meaning to me. He said something along the lines that moxie used to be some kind of beverage supposed to give you strength or something -a kind of last century Red Bull. Then the word was no longer associated to the original meaning -the beverage- but the idea of being strong remained. I think B mostly used it as someone having courage... so "you have no moxie" would be "you're weak", "you have no courage", "you have no get-up-and-go", etc.