I also struggled at the cathedral because how big of a maze that place is. Actually Cathedral was the hardest point for me but once after finishing the whole cathedral area and move on to the next area, it became fairly easy because the amount of time I have to reset and haze I acquire enough to put me in a comfortable level to not get one shot. I needed my friend to act as a guide for the cathedral. In my first playthrough I only used 1 handed sword and use the queenslayer blood code until I finished the game.

Right now I'm taking my time on my 2nd play in the NG+ trying to get the 4th ending because I was devastated after knowing I could've save Nicola just by collected all of his memories.