I coated the edges with a thin coat of WEST SYSTEM Epoxy before applying several coats of varnish to the wood. You could use paint if that is what you prefer (I enjoy the look of the teak plywood, varnished). You could skip the epoxy and just use varnish or paint, but epoxy should result in better protection. You will need to overcoat the epoxy after it dries with a UV-resistant finish, since epoxy is vulnerable to UV degradation.
You really should also coat the insides of the vent slots in the panels as well, those are harder to protect (I accidently completely sealed of a couple of them when the epoxy cured faster than I expectd!), but the original panels fro mmy boat had delamination around the slots as well as the top edges. OH, and don't forget to coat the inside of the slot for the locking tab!
I replaced the originals in about 2006. The pics of the freshly varnished new panels are from today, the stainless -steel plate that protects the wood around the locking slot has not been reinstalled yet, I need to apply one more coat of varnish first.
(Thought I had a pic of the replacement panels installed on the boat, but can't find that shot!)