Not sure how it would work on paracord.
The beeswax/neetsfoot oil is applied hot, about 140 deg. Dip the handle into it and let it set until the bubbles stop. Then take it out and wipe off the excess. It last a long time if taken care of and can be reapplied later if needed.
Also, if your knife gets rust under the skin just pop the stitching, clean it up and restitch.
Here's a link I found for making a kydex sheath. It's pretty helpful.