Grimoire most certainly does not equal skill. Ran into a warlock lvl 13 with 4500 grim, used only a shotgun. Ran into them again in skirmish, they couldn't even win a primary fight. Keep in mind I was using a nifty biscuit I got from PoE so we had equal playing field. Still crushed them and was promptly called a y1 scrub for using nifty.