As long as the Ninja doesn't have to rely on consumables to actually tank I have no problem with them becoming a tank. FFXI Had the problem where 1% of the actual Ninja tanks used their tools like there was no tomorrow, and they were awesome tanks. However for the rest of the 99% they barely used any tools, if at all, and failed miserably.

The rest don't look bad, although when I think of a Dark Knight I think of 2 handed weapons, not 1. Of course I'm a little biased since my EQ and FFXI days.