Shock in watts?
"the power of the shock was calculated to be approximately 3.9 Watts – enough to make Catania flinch and pull away"
Electric fence energisers are rated in joules. I assume this is because energy is correlated with unpleasantness.
Mine runs at 0.8J. I'd rate it about 6 on the psychological damage scale, or "not doing that again, even for beer".