Wow, heating the paste wax up sounds like a great idea. That makes sense and would really help polishing boots for dry weather use. For wet use I would still go with oil.
Grease the boots first, with a heavy duty boot grease like Snow Seal or Huberd's Shoe Grease. Use a toothbrush to work the grease into the seams. Let them dry. Then warm them and melt in a whole can of Kiwi paste wax. Boot grease softens leather and makes it vulnerable to damage. Paste wax hardens the surface and protects the leather from cuts, while sealing in the grease to keep the leather flexible.
I have two pair of boots, a pair of Danners that are about 20 years old, and have been rebuilt once, and a custom fitted pair from Clemons Boot
Clemons Boot Company - Home | Facebook, which only cost a little more than the Danners. Between the two pair, that's about $700 worth of boots, so I take care of them. I had a pair of Red Wing boots in the late '70s that had to be re-soled, and I wasn't walking on concrete. The uppers didn't warrant a third set of Vibram. After that I had worse luck with a couple pair of Red Wings, which is why I switched to the Danners. Then they moved offshore. I figured if I was going to pay $300 for a pair of boots, I would go the custom route.
Having two pair of boots simplifies the annual maintenance, because it takes a couple of weeks to let the grease dry.
BTW, I do the same service for my wife's boots. She has a pair of Ecco boots that are 20 years old. She goes everywhere in them in bad weather. They are soft, well broken in, and waterproof.