To me it makes sense that a shield would be needed to use the Stance.
I also think this should apply to Paladin DoS, in order to use their Stance.
Does this mean I am right or wrong, it just means I have a different view on those stances. To me they way they are implemented in some builds is more like 'exploiting the PrE', circumventing the design concept behind it's conception.
That is just my opinion.