'Blur' does seem like a bit of a waste of skill slot and resources, as does the active ability from the medium armour skill tree. Although I have only tested them on the PTS to see if they are anything new/useful.

'Blur' could be useful if it also reduced damage taken slightly (why do nightblades need their damage increasing?), say 15% dodge chance and 3% damage reduction from everything. Or even one of the morphs have 'passively reduces damage taken by 0.1%'.