In addition to splines, veneer, cast resin tips, etc. it is also possible to wrap the tip of a paddle with fiberglass. When the riveted metal tip protectors on our wooden whitewater kayak paddles used to wear out, we would replace them with several layers of fiberglass cloth. It surrounded the tip on all sides, wore at least as well on rocks as the original aluminum tip protectors did, eliminated the rivet holes and the pathway for water into the blade that they created and could be ground off and replaced as needed down the road (or river, as it were).
For a whitewater paddle, we might use four or five layers of fiberglass cloth for durability and it didn't seem to make any noticable difference in the weight or balance when compared to the original metal tip. Most folks aren't grinding wooden canoes and their paddles down shallow rocky rivers these days, so a layer or two of glass cloth would do fine. By filling the weave texture with resin filler coats and a bit of feathering with sandpaper, followed by varnish, the glass tip-wrap would blend into the wood pretty well. On whitewater paddles, we didn't care much about that and just wanted to build some serious bulk and abrasion resistance into the tip, so the glass usually just got cut off cleanly while still green, leaving a raised edge and then the tip was painted.
The trick to getting strips of fiberglass cloth to wrap around the end of the blade without bubbles or pulling away from the wood as they turn a corner is to cut the cloth strips on a bias (diagonal to the cloth weave). Then you brush a thin coat of resin on bare wood in the area, set the cloth into it and start gently "massaging" it into position with the brush. The weave will move on itself as needed and it will slowly take the shape of the tip. Once one layer is down tight to the surface, you can add another, sticking it into the wet resin, adding a little bit more and massaging it into shape. When all the layers are on, you wait until the resin has set up, but is still a little rubbery and can trim the inner edge as desired with a razor blade. Filler coats to hide the weave texture can then be added if you want a more invisible look. Let it cure a few days, sand it smooth if desired and paint or varnish it.
Just another possible option that works and can pretty strong. Here is one of my old whitewater slalom paddles with a heavy-duty retro-fit glass tip. Multiple layers of bias-cut fiberglass cloth, wrapped around the tip with no seams or puckers, no filler coats or feathering (these things take a beating in use) and just a coat of paint to stop UV.