Been checking the properties of zinc.....
Stability and Reactivity Comments:
Zinc metal is normally coated with a protective layer of zinc carbonate, which forms in air in the presence of carbon dioxide and moisture, resulting in a low corrosion rate.
On that basis both the pommels could indeed be ..a higher purity of Zinc ..because of the protective layer preventing the interaction of iron/zinc.
It would seem that the sacrifical anode effect can only occur when both metals are immersed in water, this ...quite likely...prevents the carbonate layer forming....leaving the more reactive zinc exposed.
So I have to conclude that even in humid conditions, the zinc pommel would have a carbonate layer develop, preventing the interaction with the iron/steel.
My theory would only work if you constantly used it underwater........
now.....did the African's invent the aqua-lung
