This is a smaller version of a previous project, this time wrapping a small neck knife sheath with paracord. I used a 2 bight turks head knot(9 lead 2 bight with 3 passes).
I used a 10 foot length of foliage green paracord, and after making the knot, worked the slack back to the starting end, so that I could use the remaining few inches of cord to make a retention loop over the knife guard. I just worked it over the guard, then tucked it down under the tightened up knot to finish.
The knife can still be removed one handed, using a thumb or finger to slide the loop out of the way to pull the knife out of the sheath. The sheath holds the knife well enough on it's own, but since it's worn upside down, the loop of cord just makes it a little more secure.
If the paracord is needed for other tasks, it's easily untied and removed from the sheath.
Here's another neck knife sheath with a 4 bight turks head knot(17 lead 4 bight 2 passes), and used around 16 feet of paracord. This neck knife is a The Syphon.
And a Swissbianco M-Sharp knife sharpener, with some knotted paracord for added grip when sharpening a knife. Knife shown is a Victorniox Tinker with camo scales, that I've had for about 20 years.