Ah!
I have been put on the spot here!
OK - 2 methods I use in easy terms.
1/. remove old wood with acute violence plus saw, dremmel, axe or whatever.
Heat and re-shape the end of the tang.
Shape new piece of wood with a cenral tang sized hole down the middle or make a stack of wood/leather/horn/brass etc rings with tang shaped holes in the center of each. Slide new handle materials onto tang using slow setting epoxy between each layer of the stack and between the handle material and the tang. Fit rivet over the tiny (2mm) bit of tang that you leave sticking out of the end of the new handle. Place tip if nblade on a wood block and with a ballpien hammer beat the hell out of the end of the tang until it mushes over the washer to rivet the whole lot tight. reshape the new handle tro final shape, oil and polish. This is a fairly traditional method.
2/. Remove old handle as before. Heat and bend the tang into a tight eye. Take two pieces of handle wood - like full tang scales - trace round the shaped tang on to one piece and cut a rebate to fit the tang. Drill a rivet hole to fit through the eye of the tang. Put the handle together, gluing the tang into the rebate and glue the second piece of handle into place as well. Clamp tight until the glue sets. Drill rivet hole right thru the handle. Reshape the handle to the desired shape. Oil, Polish and admire This is an adaptation ot the "Henry Rabbet (rebate in american) method.
Neither method requires specialist tools - I use a blackspur orbital sander and drill, Woolies jigsaw, £ shop hand tools and files and do the carving and cutting with another Mora... the metal heating is done with a camping stove and the shaping done with pliers and a hammer I found while out canoeing.
I have not had any handles fail.... yet!
Perhaps a more experienced blade smith/ cutler could comment.
John "thats not a scar" Fenna