Brigands are definitely not giving the repond slayer animation and bonus. I think they should. However, you could argue that the compendium here does not state that they have the repond weakness. This is true, but this is the same for all pirate types: the compendium states no slayer weakness, although they are defintely counting into repond slayers. I guess the compendium has to be updated and the brigands have to be categorized into the repond slayer class. Additional update for the compendium: Pirate sailors drop expertly drawn tmaps, which is missing.
Repond should affect any and all humanoid types, that are not undead. If they're not in the category, then it is definitely incorrect.