RE: Best way to finish off a deer w/knife??
I'd probably shoot the thing any way.
If you get close enough to wounded deer often enough with a knife you are going to get seriously hurt sooner or later. Probably sooner. Those hooves will eat you up and more than a couple people have been killed getting gored with antlers.
Cutting the neck on a trophy just ruins the mount and screams amature. You might get away with a small head mount but I look at my first one every day and am reminnded of the stupidity of "cut his throat". Just darn lucky the thing didn't kill ME.
I'd use the knife to make a spear before I'd ever jump on the back or front of a live animal again. I'd think a sledge hammer to the spine at the base of the head would be safest and least damaging to the mount of a trophy animal.
My first choice would be a good shot to start with.
2nd, a good shot to finnish with.
any thing else a distant third at the least.