OK, here is what you can do. Find someone that sells bees wax by the cake.
Get 4 cakes ( I tend to like having extra around
), melt the wax, then put the handle in it while the wax is still hot, not boiling, just really liquid. Let it sit until the wax cools and hardens. Then, heat the wax up again, until liquid. Let it cool again.
After that, heat it up and remove the knife. I promise, it will not get loose again, soak any liquids, or deteriorate until the end of time.
I have naturally oily hands, so, my leather handled knives tend to darken fast, and swells the leather.
When I played baseball, I bought a fielder's glove, and by the end of the season, it looked like a catcher's mitt.
Seriously, it will work.
How old is that Marine Fighting knife?
Moose