If I have a card like breaking the rhythm can I negate a weapons bonus and will it stay negated for the rest of battle?
Negating force penalties.
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.
If I have a card like breaking the rhythm can I negate a weapons bonus and will it stay negated for the rest of battle?
No. As of Ivory Edition, Items have Force and Chi modifiers which are not considered bonuses or penalties.