To prove that grimoire takes no skill whatsoever, I decided to hunt down every ghost in the game today. I started off the day with a grimoire score of 3900. I'm currently at 4360, but I'll be over 4500 when I'm done (had to stop playing for the day and get some work done). So in a matter of maybe 4 hours of playing, I raised my grimoire by almost 500 points without using any skill whatsoever, just YouTube and a little bit of jumping. All grimoire is is an indicator of accomplishing different things in the game, it has 0% bearing on the skill level of a player.