What would Elrond know....
Seriously though, that's what seems righteous to me
Firefoot, but the way it's written in
Of the Rings of Power in The Silmarillion might make it seem that it was the severing of the finger which killed.
Isildur took the Ring, and
then Sauron was vanquished.
As much as I'd love a detailed call of the 'match' it's probably not going to happen now. Barring any time-travel.