Well as you said, pvp is kinda off. And in general the activities you describe gives grimoire - but grimoire is more based on time spent.... i had hardly done much fps games before destiny - but still way better than ppl with 4500 grimoire... further more, exp is not equal to skill. I like my scout riffle, so my grimoire is lower than ppl doing 10000 kills with hand cannons ( why play with them if i dislike them ) and i do not get any better skills by doing 100 strikes with 5 different weapons, which i never will ( as it is too boring )