Hmm.

Did a Finisher move on a tough Forsworn, who was the last enemy- lifting him into the air with my sword and plonking him down again.

After that, my character also fell dead!

Must have been poisoned.....

Hmm. That`s a point.

I was wondering if the game had miscalculated... I guess I could also view it as a last ditch strike.

More likely he had a fire-enchanted weapon and you were set on fire?

I agree, probably a continuous damage effect of some sort. Maybe you didn't notice your health draining during the animation.

Sounds likely.

One thing that happened to me many times was that I pacified a sabre cat as it was striking, then I get to see my dead body with a very peaceful sabre cat next to it.

Had this happen on a caster type enemy. Did the finishing move while they were frying me and we both ended up dead with my follower walking around muttering something. I hate being locked out of controlling my character by a finishing move. Couldn't have prevented it with a potion, but can't access my inventory.