This is now a guide.
I sanded back the tang, and applied phosphoric acid based rust converter. Waited 30 minutes, then masked up the blade, and applied 4 coats of primer paint each 5 minutes apart.
I sanded the handle with 80-180 grit paper and scratched away the rot from behind it. I bogged it up with filler and let it dry for four hours. Then sanded handle with 120 - 600 grit paper. Cleaned dust off with dry rag and painted with satin jarrah stain +varnish. 1 coat so far.