What about Klein screw drivers. Mine seem to wear out awful fast. That little black tip seems to be just for looks and brand recognition. The bigger the screw driver the longer they last, for me. I guess it because of the larger area covered on the screw. But I am not happy with Klein screw drivers anymore.
The strength of the blade and shaft goes up as the square of the thickness. It quickly reaches a point where the measly amount of force a human can put on it isn't enough to damage a big screwdriver through torsion alone.
Now, misusing it like a prybar/lever and bending the shaft, that's quite another issue, as the deflection is a function of the length cubed, and the longer the shaft, the more likely you are to bend it despite the extra thickness...
