Or maybe create peasants (including human spearmen) based on the assassin model, but with a skeleton and militia animation? (if that's even possible) I think such an option would look better.
And dwarf spearmen could be made based on the model and animation of peasants/militia, and the legs could be taken from the dwarves themselves.
And dwarves will most likely use their standard models so that they can throw spears when upgraded, otherwise there might be issues.