I believe you need to be closer to a loss to get the honor medals from a lower level barb town. Some guy in another thread posted about attacking lvl 4 barb town with 250 ballistas and getting a lot of honor medals. I tried that on a lvl 3 and got one right away but since have only gotten lion. I am in the process of decreasing the ballista count untill I start getting losses. After that I will raise it again so I win with no losses.

I believe that to be the way to get the honor medals from barbarian towns 1-4. Just use ballista and transport but you have to barely win with no losses.