Apparently Vikings did use drawing axes in history. So, why not give to the Berserk? This sort of thing has proven to be possible with the Fire Lancer unit already in the game. How would feel if the Berserk got a throwing? Every 30 seconds, they throw an axe, that does 12 damage for non elite, and 14 for elite.
Give Legionary the ability to throw pelims (a roman javelin) one every 30 seconds? Could be low damage like a skirmisher, but would be a nice opening attack.