There is only one thing I can add. Tether. My knife has a plastic sheath which has a good grip on the knife, but a good tug pulls it right out. I mount it upside down on my PFD and secure it with a tether. If anyone is going to drop something and watch it disappear into the deep it is me.

The tether is just small diameter poly rope about 1/16 inch. It is as long as I can reach from the PFD plus a foot. I coil the tether and squish it flat and then put a small rubber band on each end. Finally I tuck the tether under the knife so it is always out of the way. Pulling the knife out snaps the rubber bands, releases the tether and you are ready to use the knife without losing it.

The fishermen here use netting which sometimes get caught on coral and left behind. Hopefully I never need the knife but I feel better having it ready to use if I get snagged in netting.

~Bob