Veteran trait should be changed

I don't like how a serial killer who targets the young and a brave soldier who has been fighting since he was 17 get the same trait. Veteran should be given to army units after a war, so all already enlisted soldier units of any of the belligerent countries involved, winner or loser, should get that trait after peace settles. Units that get a lot of kills should be given another trait, like "Cold Blooded" or just "Killer"