But twice now I've run up on someone, had full HP, gotten stabbed in the stomach and thrown to the ground, dead. One had a dagger, one a broadsword. 99% of my kills are sneak/Shadow Warrior kills, but occasionally I'll get someone down to half HP or so and then get an instant kill animation before one more regular hit would do them in, so I guess I can do it too. But I don't know what it is that's triggering these kills. (The only one-handed perk I have is the first one, maxed out.)
What's doing this? I play on Expert, FWIW.