Thanks for the tips man! I had no idea you can block with LB. Must have missed that tutorial. I thought deflecting was the only means of blocking. That helped immensely. Beat him first try after your tips!In the second phase you should try and wait for the lunge which he winds up, and stay at medium range for it. Every deflect counts but focus on the red critcals and then guard or dodge through the normal swings.
You can hold guard LB/L1 and then hit B/O to deflect at any time. It helped a lot when I figured that out, because I first thought you should either wait to deflect OR guard but you can actually keep guard up a lot of the time and deflect from there. To mitigate some damage. With the Enhanced Defence wizardry + guard up I didnt take much damage from normal swings, except for draining the spirit bar..
But just focus on deflecting and punishing those until you get fatal strikes. And recast the enhanced defence each time hes down.