Shaft worn in areas, dings and little chips
Sand the areas that are worn and grey looking with 100grit sand paper,
then coat with a marine varnish or a 2 pack polyurethane.
Once this is dry re-sand this area and the whole shaft ( to get a better finish) with 150-180 and recoat, dry again and then a final 320 grit sand and apply a final coat.
Remember to not coat anything that has not been touched by sand paper, as it will not stick!
Holes or dings in the blade.
The best would be to use some epoxy, fill the hole level, sand the patch down level and lightly then sand the whole blade on that side ( or both sides of the blade to get a complete even finish on the whole blade)
Recoat with a marine varnish or 2 pack polyurethane.
Cracks or splits in the blade
Basically you need to open the crack up make sure it is clean, put some epoxy resin in there and clamp it tightly shut again to it's original shape.
you can use packaging tape to hold it to shape and close the gap as much as you can.
When dry, sand down the excess resin back to the glass layer ( through the varnish), recoat with a thin fibreglass over the sanded area only, sand this glass level when dry, then apply some coats of marine varnish or poly urethane, sanding between coats.
Again, remember to not coat anything with resin or varnish/ polish that has not been touched by sand paper, as it will not stick!