The sky's the limit. Some paddlers are using epoxy, varnish, oil or nothing at all. I've seen vacuum bagged glassed ones. Some just coat their tips with epoxy and just oil them. (linseed oil and terp. etc.) Cedar as you know is soft but feels great in your hand oiled or natural. I've epoxy coated cedar and it makes it tougher but needs maintenance. Some people do inlay ends of bone or fake bone type of things for abrasion resistance.

I personally feel that no matter what you use on a cedar paddle, it's going to get dings unless you hang it on the mantel. You can always start natural, go to oil, then to epoxy or varnish, re-sand and back to oil. Use it and enjoy it.