I can tell fromsoft admitted a shortcoming considering they never again made a black (red) phantom npc more frustrating.
That one asswipe with the tower shield in 4-1. He's scripted to never allow you to backstab, considering he spins around to face upu faster then any player could. Not to mention his spear somehow breaks armor and shields very easily.
I aint mad though, like I said From admitted this mistake and never did it again.