His weakness is in the wine, but it is truly the fact that he prides himself on being a wine expert. Because of this Montresor plays him saying that Luchesi isn't as great at wine as he says he is.
The opening passage talks about not being happy with the pennies she had even though she had bulldozed with the grocer and the next day would be Christmas.
The answer could also be unhappy, but it is most likely dissatisfied. Cheers