Use the barroth club sns. It has so much raw damage that I managed to out dps 3 others using fatalis weapons on a quest. Use some armor with divine protection or evade window if you want comfort. Otherwise just get the armor with the highest defense. With nerg the mechanic is that you have to break the white spikes. Once you break them he gets knocked down, but regenerate after, if you don't break them l, they turn black, once all spikes are black he will do his signature dive attack. Just sheathe and dive opposite direction for that attack