Taking over windhelm, since patch 1.9 this is the first time i experience this.

Level 20 Nord, 200 health and 170 Stamina.

The small area where the blacksmith is, i keep getting insta killed by the enemy, even with health 180/200.

Tackled that area four times now, lowest health i had was 142/200 and still they start the animation.

With over 750 hours playing this game and trying various classes and builds, this is the first time i experience the enemy starting an insta kill animation with such a high health (low health is known).

This is the first time i try the civil war with patch 1.9 (PC).

Anyone else getting this?

were you getting kill cam on your instant kills if yes its well known glitch

I haven't done this quest with 1.9 yet, i might try it now and see if i have any bugs.

It might be cause of your health isnt too big and the NPC's attack damage is simply that high (Weapon with enchantment/weapon skill high, high perks for their weapon class, etc)

Yes, it is a known issue. I've suffered from it now and then. I used to have high health like you, then I took a bugged kill cam to the knee.