One of my tactics on the hard difficulty is to stun like crazy and preform an execution animation. I hardly even take out my weapons. I love parrying and I unlock the projectile parry skill very early on.
Also
Also
If you stun enemies in Niflheim and do the execution animation (e.g. beating on ogres heads, punching the warewolves/revenants, etc.) you freeze the timer on your rate of being poisoned while killing off the enemies.