As well as being a major narrative development for Mordheim, it's a pretty interesting rule-set -- a non-combatant, pure-good character, with a capacity to 'convert' enemy fighters. & a potentially exciting inclusion as an end-of-campaign event.
I also really like the remarks about how Sigmar rejected the idea of a divine ruler for the Empire as inevitably tyrannical, given the direction things have gone in the Age of Sigmar....