I know it may be a bit stretched, but I think it would be super cool if you found a way to make the saved files from Book II and convert them into files for Book III. Then, the starting creatures, instead of being something new, or something that was a starting creature before could be something that was supposed to be pretty hard at the end of Book II. Then, players could start with what was the best sword in Book II, but in Book III it's pretty much useless. They could also keep the skills they spent time to level up etc. I'm not quite sure if it's possible, but if it is - even if it's only the skills they can keep, it would be super useful, cool, and it would make players happy.
well, in the end of book ii, if you followed the main storyline, the end cutscene mentioned your equipment being gone, so I don't think the weapon idea would work