I believe the change to the black blade was a little to harsh. If the duration is to be changed for two turns then could the time to cast it be changed for two minutes? Or perhaps it remains out for six turns with a time of four minutes. This would allow time for the epic ability to be available.
With the removal of skills points I would also request the class is given some of the skills which would allow it to enter into the cross class specialties and the feats which allow harbinger to cross class work towards some of the other classes..
In my case I would love to make a Harbinger / Shadow Dancer however even before the skill point change with an 18 int it is a struggle to have the skill points needed. With it I would need to move to a secondary class to take the build. Perhaps the Lurker feat could behave like the Shadow Mage path and allow choosing the PRC without hide and move silently with the cost it does not grant the sneak attack.
Could we also get spellcraft? This is the only class with spells without it.
I am enjoying the class even with the changes. I personally build for flavor with the class helping telling the character's story. I am not a power builder. No spreadsheets and I have no idea if the above feedback and thoughts would allow a power builder to crush and slay everyone.