That first one is ones of the hardest bosses I have ever faced, however I did not use Living weapon or any ki maneuvers really. After I figured the game out a bit, it became much easier then any launch Souls game.
The bosses have been quite easier than they were on the demo, to be honest.
The first boss was the one that killed me the most, but because I kept trying to rush it so I could sleep, lol, anyway, I think I lost 3 times for it.
Also never used the Living Weapon/Spirit Guardian, and I'm going with the katana.