I would venture to say that two handed dedicants have a much wider range of utility with Templar's defense, seeing how there is what, somewhere in the range of 20 different moves you can do with that.

This is not to belittle shield dedicant's, who can be tanking beasts, they just do not have the wide ranging skill that is templar's defense. And Angel's Wing does not quite equal out in the end, seeing how it only provides three different effects.