Knowing their stats at the second-to-last upgrade, on the other hand, would be quite useful. To get the last level you need to spend a slab, and there's only so few of these per playthrough, so you can only get so many fully upgraded weapons. It would be very useful to know which ones to spend those slabs on, and which ones can be left at +4, +9, or +14.
Other potential use: in another thread right now I just made the point that, when comparing Crystal weapons, you should really be looking at their +4 stats versus a Regular weapon at +15, since you definitely don't want to waste a slab on a crystal weapon. In this scenario in particular, having the Crystal +4 stats would be very useful.
And it would also be useful to add Chaos +5 +10 Humanity. Chaos is really considered as an elemental upgrade path, rather than a scaling one, so to properly compare it with other elemental weapons we should know its full strength. Rather than say "Chaos might be as strong or stronger than lightning when you have 10 humanities" it would be good to know for sure, especially since it wouldn't be difficult at all to get that info.
I guess since those pages have been untouched for so long I thought I'd check with the community before hacking away at them! But what do you think; is it better to know those +4/ +9/ +14, and Chaos +4/ +5 with 10 humanities, or should I just leave it be?