I've heard two suggestions regarding wax... 1. put it on your line-cutter to avoid rust 2. put it on your lines to avoid wear.
Dripping wax onto the line-cutter seems fine... hint: I just took mine apart - probably better to not do that. Pain in the ass re-assembling. Better to rinse it well; make sure it's dry, and just drip wax onto the metal parts and into screw holes. Parrafin / petroleum-based wax might absorb less water than beeswax, but haven't looked it up.
On the lines, I am thinking on the thicker braided portions - but I have concern that it might cause sand to stick to the wax, which might make wear worse! Main lines aren't rubbing things that are wearing them; it's more about stretch/shrink or abrading them on rocks or other line tangles.