As far as defensive vs. offensive, I feel it will sit somewhere between PLD and WAR so as to not overshadow either in their preferred play-style.

As far as how their tanking will work, that is a tough one.
My guess is it will pull a little from both and then have its own thing on top of that.
It will probably have both some drains like WAR and will have a slight emphasis on Parry sort of like a PLD and block.

It would be pretty neat if they used self-shields sort of like insta-cast stoneskins to mitigate damage, going with a "cloaked in darkness" defense method.