I can't help you, but are you having trouble with his powered up form? If you are, I'll let you know that you can stagger him out of it. Making the fight much easier.
I haven't killed chester, because I want him to invade in the township, and I don't really want to go all the way to get the wanderer set (and I just noticed I only have heavy armors except for the dingy set amd the thief set).
If you didn't resolve, give me a wack on PSN when you sign on. I could help you quickly to kill him. He's not that bad when he's not focus on you. But with a mid roll you can avoid most of the big damage and make sure to always 2H hit him when he start to power up.