It basically doesn't, IIRC, outside of maybe a couple of dialogue options that can give you some extra relationship points with the relevant characters? Like you can't just tell Khelgar 'Cool, I'll teach you how to punch things' - he still has to resolve his personal quest line so that he feels like it's ok to commit to being a Monk now (he's more useful as a Fighter anyways, his stats are all wrong for Monks.)