I found Nito to be a lot like the Four Kings, much more dangerous from far off than right up in their face. Four Kings have the direct hit system working against them, where they hit you with the handle of their weapon and barely plink at you if you are basically in their model, but stand a bit out and their melee+magic is very deadly. Similarly with Nito, my first playthrough I killed him by 2Hing the Quelaag Furysword and getting as close as possible and just wailing away. Most of his attacks just sailed over my head, and the only one that did hit was his magic explosion that conveniently kept the skeletons down. Never uses Gravelord Sword Dance when you are that close either.
Of course, now when I fight him I use a bit more finesse and actual strategy, but I was surprised at how much he didn't kick my ass when I got all up in his face on my first playthrough. I definitely got a bit lucky but still.