[b]Grimoire is an indication[/b] The best example everybody probably knows is time played in a game. When you see somebody that has played Halo, Assassin's Creed, or any other game for 10 hours you get an indication this person might not be that good yet. It's normal that somebody that has 50 hours in these games probably knows more about it, and ultimately has had more time [i]mastering[/i] the game. In Destiny these values can be multiplied by 10 easily. So 10h becomes 100h (beginner-novice) and 50h becomes 500h (experienced). This is because of the RPG nature of it, and more hours means stronger weapons and armor. Now grimoire ties into your time played. A lot (though not all, see spoiler!) grimoire comes with more time played. Seeing somebody with a high grimoire [b]usually[/b] means they have a high amount of time played, which means they have had more time mastering the game. [spoiler]I have a great example on my friend list: completely insane number of hours (1200-1500h), but not such a very high grimoire. Some grimoire doens't come naturally if you don't hunt for it. [/spoiler] In the end, it's an indication. There are people that might have played a massive amount of time, but might still be poor. There are people that might have played a small amount of time but are great. There are many exceptions, therefor it's just an indication. TLDR: [i]usually[/i], grimoire indicates the amount of time a player has put into mastering the game. That doesn't mean that people with talent can't be better, since they might exceed the total skill level with less time needed/less experience.