I solo'd this quest entirely as a NIN40/WHM20. The NM hardly hit me. Only complication was when he did Soul Voice followed by a Minuet II and then did Horde Lullaby; it hit me for 288 damage before I was able to recast Utsusemi.
I equipped myself entirely in +Evasion gear and ate a Jack-o-Lantern. Where I couldn't add +Evasion, such as rings, I wore +INT to decrease resists and increase damage of the Ni spells. If it weren't for its spells, I could've easily Ni tanked it.
Others should try it.^^