Wow, this has moved on....
I suggested using the block of wood when you rivet over the end of the tang for one reason. If you clamp the blade in a vice, it needs to be damned tight to stop any movement and hence marks on the blade. Which you can cure by clamping the blade between bits of wood or leather - but they don't always grip as much as you'd like and the blade can move in the jaws and you get a good rivetted end but a loose handle.
In using the wood, you can ensure that it is upright, and control the handle end with your left hand as you hammer with your right. Protect yourself from the edge by having the blade wrapped in many layers of tape. Don't whack it, as you can easily skew the blade sideways and bend or break the tip off, as well as being dangerous to exposed body parts. Use controlled taps with the hammer and look to see that the rivet is forming correctly (like a mushroom) and not leaning over to one side.
Ogri the trog