The black knight seems a little strong. +10/20/40 to hit and damage for charging 100 ft at lvl 6/10/16 seems overkill. Charging only 30ft doesn't make anything super crazy happen at any level but the long charge to initiate. Combat is a little scary. Especially if you were to crit. A flat +40 or +80 or more depending on your weapon seems kinda strong from a single source.
The idea of having a black and white knight is awesome I think, but maybe scale down the bonus to +1/20ft charged at 6, +1/10 ft charged at 10 and +2/10 ft charged at 16. I asume that these bonuses are on top of the charging bonus too?