Units with this rule may gain one of two different sets of effects depending on whether they show up Sober or Drunk on the Battlefield.
The Drunkard unit is miraculously sober for once. Sober models gain Vanguard and Light Troops. A unit that has been Sober once loses Scoring for the rest of the game.
The Drunkard unit is unbelievably drunk. Drunk models gain Immune to Psychology and Thunderous Charge. Drunk units cannot Ambush.
The player must choose before the battle whether a Drunkard unit is Sober or Drunk. Drunk Characters cannot join units containing any Sober models, and vice-versa (models without Drunkard are considered neither Drunk or Sober).