A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
A player, 19 April 2010
Text Berserker Battle: Once per battle: Give this card +2F. When Force is compared in this battle's resolution, if this card is in your current army and that army's total Force is not greater than twice the enemy side's, destroy this card after the battle ends.
Is the "Once per battle" clause there to overwrite the fact that abilities are usually only used once per turn? Say I was defending and I used the Berserker's ability to give him +2F. If he survived that battle and I moved his unit into another battle, could I use his ability again to give him a total of +4F?
Dan Jacobson (rules official), 19 April 2010
Text Berserker Battle: Once per battle: Give this card +2F. When Force is compared in this battle's resolution, if this card is in your current army and that army's total Force is not greater than twice the enemy side's, destroy this card after the battle ends.
Is the "Once per battle" clause there to overwrite the fact that abilities are usually only used once per turn? Say I was defending and I used the Berserker's ability to give him +2F. If he survived that battle and I moved his unit into another battle, could I use his ability again to give him a total of +4F?
Yes.
The "Once per battle" clause overrides the default "Once per turn" restriction in the rulebook.