The Blackest Night, skill improvement.
I want to suggest a simple change to "The Blackest Night", it wont effect the overall use of the ability, but grant the Dark Knight a lot more party support.
If Blackest Night is not fully absorbed, make the remaining Shield Points turn into healing.
There are often situations in dungeons where a healer dies to a boss and as a dark knight you and the dps just slowly die and you can't do anything against it. Any other Tank can easily keep the DPS alive during a dungeon boss but the Dark Knight is just frustrating in that regard,
If Blackest Night had a healing function you were able to keep the DPS alife a lot better.