The duke's monocle increases persuasion by 35pts, while the gable's cigar only increases it by 24pts, so that's 11pts of extra persuasion power. Depending on the requirement, those 11pts may be enough to complete a quest which you were unable to complete before. The duke's monocle in question can be found in LF2, chapter 7; after you recruit a certain person. I don't want to get into spoilers too much beyond that, but the walkthrough covers it in detail if you want to peek ahead.
flavie wrote:The walkthrough teaches us things we couldn't have noticed! Though it doesn't say for example who and where killed 10,000monsters.
It actually does.
At the very end of the LF1 walkthrough it recommends an area and a character to do the quest with. It also says that it's time intensive and that the reward is not worth the investment. LF2 started off from a save that had already completed the quest back in LF1, and just never revisited the quest again.