Originally Posted by
Meataus
Ok, I think I've finally figured out how this works.
First, to gain get to veterancy in one fight, your unit has to kill enough so that it would gain one whole level if it were a single player battle. This varies depending on your unit, i.e your katana samurai have to kill a lot more enemy than your yari ashiguru to get to level 1. As with single player you get lots of juicy xp for killing routing units so factor this in.
Once the battle is over, it will look at all your units that killed enough to get to level 1... and then pick the cheapest and offer to let you make it a veteran!
So make sure the unit you want to get to veteran killls enough to level, and is the cheapest non veteran on the field, and it will always work.