When you say "sterilisation" what do you mean? All you need to do to clean a razor is wipe it with some barbicide, so dont go down the road of autoclaving it or boiling it or anything.

An autoclave or boiling will wreck the scales (unless theyre metal) and may damage the blade as well. Barbicide is all you need.

In terms of treating the wood for waterproofing, check out the Workshop forums as they give details of how to waterproof wood. Popular methods are CA or epoxy finishes as they are hard wearing and take a good finish. I'm not a resto guy myself, so I cant give specific details as my knowledge is sadly lacking there...!