You wiring is old. The solution is not to use a band-aid, but to replace all wiring. Old wiring will have poor dry-rotted insulation around the conductors.
The 3rd wire ground is not the same thing as simply an earth ground. Simply adding a 3rd wire ground, if you could, would not be a solution for safety, and would not pass code. Any wiring over 50 years old should be completely replaced for safety sake. Actually, the old knob and tube is safe because conductors are in separate walls.