What you DON'T want to use wax on: metal ferrules, as found on bamboo and early glass rods. And it pays to keep the metal clean and free of tarnish (I like to use Simichrome for the tough jobs, but all that's needed for regular maintenance is rubbing alcohol and a q-tip.)
Candle wax works fine for glass and graphite ferrules. If you find yourself using a rod with loose glass or graphite ferrules, beeswax will do as a temporary fix, in a pinch. That's because beeswax is stickier. But beeswax also picks up dust and dirt much easier than ordinary candle wax, so it's important to be careful about cleaning it off when you break down the rod. And it's important to get the problem fixed, before the tip blank starts to get stress cracks. If a spigot ferrule is fitting all the way up to the hilt between sections, it's too worn. There should always be a small gap, as there is with new rods.
The long-term fix for a loose glass or graphite ferrule is simple: clean the ferrule with a wet wipe and some rubbing alcohol or Coleman fuel (which should dissolve any wax residue that's on the male ferrule or the spigot.) Clean the female ferrule too, using a q-tip, because you will of course be fitting the ferrule into it after the repair.
Then mix up a little epoxy- or Permaflex, as suggested above- and coat the male/spigot ferrule. Give it a couple of minutes to set- but not enough time to harden. Then, while it's still wet, wipe it all off. A thin layer will remain, like 1/000 of an inch. The only thing you should notice is that the ferrule is darker where the epoxy has been applied. Let it harden completely. Then try fitting the rod again.
I've done this to a couple of different spigot ferrule rods, and that's all I've ever needed to do to the ferrule joints back to their original fit- the kind that leaves a little gap between the sections.
But if it's too loose, just repeat the process. And if you find that you've overdone it a little, just sand it down ver-ry carefully with #0000 steel wool or 2000 grit sandpaper. Once around, clean the ferrule, check the fit, until you get it.
I think that for the purposes of this repair, any good clear epoxy will do. I've used the 30-minute set epoxy with no problems.
Also, I was told once by a rod repair guy that it's always a good idea to use just a little more resin than hardener when mixing- too much hardener and epoxy tends to stay sticky. Err in the direction of 60% resin/40% hardener. Remember to mix thoroughly.