Boss battles can be over in a minute if you time your spirit summon right. Learning to parry is all you need to do. Chipping damage away with your weapon is useful yea, but it's not as impactful as parrying that super move by the boss. When I got killed it was 80% of the time failing to parry.
I finished the 2nd part twice. I've got a level 18 character I'll transfer over. I kinda liked the first demo more, but I've had fun with this demo. I don't know how to explain it. It feels a bit different.