As a Naginata my dps is pretty bad as he teleport out of Broadside pretty fast, I always kill him with about 1-2 minute left, which I know is slow. I have no idea what build would be the best...
But the fight is pretty straightforward except for that damn Winter Storm, it's a pure one shot. There's a fire circle in the middle of the arena at the same time, and staying inside it give complete immunity. It's starting to be a common mechanic at this point but the visuals are pretty unintuitive.
His other attacks are easy to get, the red bone spear deal big damage over time but is slow and the warning shine big, the lightning is very often hard to avoid, so I recommand maxing light res first if you have to choose. He also have a cold aura and sometime put some fire on the map.
4 Harvesters start to move after some time, and deal big poison damage when getting close to them. The poison zone can be avoided so in general it's better to not stay still when they are close, simple as.
Oh and don't make any town portals inside his arena, keep it in scosglen if you wanna go back in town to buy potions.
I recorded one of my fights, if you're curious :
https://www.youtube.com/watch?v=4d5a_nMoLvA&t=82s