Personally, I'd avoid epoxy for rust prevention, but I'm pretty picky about finishes.
If you're going to be using the knife, wear and scratches in the softer epoxy (especially on the flats) will be visible.
I'd expect it to yellow with age, especially if left in the sun (epoxy doesn't like UV--there are expensive versions with UV inhibitors which might be OK).
Also, if you leave it in the sun, the heat from the blade will make the off-the-shelf epoxies feel soft.
I'd say try it out on a 'throw-away' knife and see how you like it before wrapping it up and all. Maybe it'll be what you want.