I think you are right with the grimoire, im a casual player with around 3900 grimoire i dont have all ghost and fragments so put in 500 for that. Almost there if I ever want to find them all. But it takes too much time i rather invest in other activities. Maybe 4600 is a bit steep, but i would prefer it then Light level requirments. Pvp kd depends which pvp mode rift is killing your kd haha