Torque wrench- anyone got one I could borrow?

Still no qualifier !

If the wrench that left the groove in your hand was 1 inch long that would be very different to doing the same thing with a wrench 1 foot long.

Weight + the leverage (in inches, cm, feet etc) - you need both !!!

The spanner in question was 6" long, I weigh 79.7 kilograms- does that help?