When milady is being taken off to her death D'Artagnan impulsively steps forward and Athos says, 'One more step, D'Artagnan, and we cross swords.' Which is from the novel. But in the movie he adds 'And this time I won't hold back.' Just, y'know, to make the implications crystal clear to the audience.
I have a certain sympathy with the author of that thundering clanger. How much can you leave unsaid and be sure the point is made? It's the writer's bane and must go double for script-writers. Unlike scriptwriters, a fanwriter can write to her own sensitivity on these matters-- infuriating though it is to those who aren't good at supplying what's left unsaid. I was cheered to see a professional reviewer remarking of a professional novel 'and I wondered if this was one of those books that tries to leave the reader with the impression that they just weren't bright enough to get it.' So it's not just me. There are certain pale as water fanwriters whose works are distinctly short on both action and emotion, and whose inevitable pages of comments- 'Wonderful!' 'Oh this is great!' 'Marvellous detail!', the small-minded or the cynical will mentally translate as Nice suit ya got there, Emperor.
In the Musketeers case, though, I think another besetting sin was at work- which I confess to as well, so it's doubly annoying: the rhetorical flourish. The unnecessary remark or line of dialogue just sounds so good in your head that you have to include it. So it's obvious. So it draws a line and paints great big arrows at it. So what? It *sounds* good. Must have it. It's unfortunate that these dramatic flourishes, by some perverse law, are almost always borderline adolescent and that you just don't see it while they're ringing in your head. Three years later- god, why did I put that line in? It's obvious and amateurish. Ouch. (I've had to stop reading people like Eddings because he *would* not stop putting heavy sardonic remarks in the mouths of his characters. His notion of wit: like the fanwriter mentioned on fanficrants whose notion of a high-class restaurant where the British nouveau riche would eat was IHOP.)
ETA: nothing to do with this but I-am-a-suck-for-a-pun. Ad houyhnhnm attacks, bwuhhynhhynhhynh.