I don't know if going into a huge amount of detail on every fight is such a great idea. Mainly because with the amount of fighting in the series and the amount of people who check out the encyclopedia without having read the later volumes. It would be a big task and might possibly ruin the effect of reading them for the first time for people new to the series. I still think it's a cool idea if you document each fight and when it took place in the series, but leave out the spoilers if possible. That's my opinion whether it matters or not.