That is an very interesting post Atilius.

As I made the same experience described above when useing to play Barbarian fractions in BI. Actually I play the Sassanids and am get promoted with traits and battle stars much more often. Maybe nearly as often as in regular RTW games.

I can imagine that any fraction that can use to become a Horde get a penalty to keep their battle skills at a low level. While using to be a Horde, I made many battles with my big armies. When promoted normally, I would have got lots of battle stars for many generals. If I am right, this is made to help those fractions not to be able to form a Horde. On the opposite it is annoying, because generals with so many battles will not get promoted and this is not changing a bit after your Horde settles down!

traits:
After you settle down with your Horde, you are forced to build up your cities and form a real army. In conclusion you have to use money you made while looting in Horde mode. You are forced to spend much more money but your actual income over a big time. This IS still affecting your generals. If you leave them in a city when you end your turn, the very next turn you will earn nasty traits that affect your administration and monetary skills. Stay out of your cities in this phase of the game!
Same for religious penalties: A pagan general that is used to be the governor of a Christian city with big improvements (as cathedral, monastery and so on) will start to loose his fait into his own religion. Same goes for Christian governors in highly improved pagan cities – or more likely in Zoroastian cities! It is better to avoid this when possible, which is often not.