The quest in question, "Up in Arms" is probly already complete on your character. That quest had you talk to Gerolt, then talk to Jalzahn, then it was done. It doesnt stay as an active quest in your journal, it ends right away and moves to your completed quests section. The next step is to gather the atma, then go back and talk to him again(with the zenith unequipped) and he'll complete your upgrade. So equip your zenith and go do some fates. The drop rate on Atmas is pretty decent last time i went through. If you dont get one in the first 5-10 fates(provided youre in one of the correct zones) then maybe theres some other issue.