I would think that if you were in its coils with one arm free, that a sharp small knife would be better than a large chopper. With incentive, I can cut through a slab of meat the girth of a man's thighs with a SAK in less than 30 secs probably, and so can most of you. I mean I've cut through a roast using a kitchen paring knife. Muscle is meat. Cut across the grain of that meat and the entire length of that muscle is useless because it no longer has the connection to contract across its length. I don't think a snake is one long piece of muscle so you'd have to cut through several areas to totally disable it, but I'll bet cutting through one section is enough for it to let go and try to get away from you, not because it's totally disabled but because you'll have hurt it more than it cares for a meal.