I wouldn't say it was sexist (I think that's the term you wanted, not racist). Some of the characters, such as Inquisitors or Assassins, could have easily been female without too much of a change in model.
I've got a poster showing all the HoMMV units, and only a handful of unit types are female.
Assassins look female enough to me, true, but Inquisitors are definitely male, with their pronounced jaw bone and wide shoulders. And beard.