Ok... Now taking my OP-as-all-getout Breton for a little test:
Inside Breezehome, spawning my very own Bandit Chief, using player.placeatme ff001afe (this is the last ID in the list if you search "bandit chief"... for me it spawned a guy in full steel plate with a Dwarven Greatsword). Selecting him and typing getavinfo twohanded, I see his skill level is 79. I also did addperk 52d52 to give him the Devastating Blow perk (I got confirmation that it was added, seeming to indicate that he might not have had it already? Not sure about this). Finally, I did player.setav health 10000 as suggested, and against my better instincts, drew no weapons...
And this was all worthless, because he was immediately set upon by Lydia and my loving husband Vilkas, who together made short work of him.

I forgot my house was so crowded, LOL.
So then I fast-traveled to the Lord Stone. Thankfully I didn't have any followers, but Frost the horse appeared with me, so I rode him off away from the place and came back and spawned another Bandit Chief, same stuff again...
My full health at this point is actually 10118, so I do a player.setav health 9882 to make it an even 10000. He hit me once with a regular attack. It did no damage to me, but he was damaged instead (darn Ebony Mail), and yelled "Victory is yours! I submit!" and ran off to hide behind a tree. So I gave myself a normal Ebony Armor and switched equipment. Now he started attacking, but he's not taking away any health at all, and is alternating between blocking and power attacking.
Test is ongoing...
Edit: Okay, 20 minutes was enough. He was in fact damaging me (a whopping 30-ish points) but my regen rate is high enough that it barely registered. He did manage to stagger me a fair bit of the time, but no decapping. BUT. I did a getlevel on him, and his level was 28, and the character I was testing this on is level 50, so I'll try again later with a lower level character.