I have also refurbished my steps and companionway because of sun, UV fading.
Used about 400 grit paper to key surfaces, then a wood stain of the appropriate colour, to bring it back to original, then a satin finish floor varnish, put on with foam blocks cut from a sheet used as a paint brush, no lines, perfectly finished.
Shown this method by boat builder on the Hamble river.
Hope this helps.
Odysseus.