I read a bit of speculation about the lightsaber. Or maybe it was just me and Neo making things up. Anyway, the idea was that the the saber is actually supposed to be a bit crap. Notice how much the blades flicker and flare, probably more than could be explained by the snow. One idea was that it's an ancient lightsaber with a design that fell out of style. Another ties into the whole Force Awakens thing. This guy came into the Dark Side on his own and has no formal training or mentor, maybe just some lore he dug up. So his saber looks like that because he doesn't really know what he's doing, only that it looks cool.