Simple, during the reinforcement window, you are capable of storing gear you don't want to use in battle.
You put them into crates, and thus they won't show during the battle.
Why?
Avoids the overkill on gear bug that makes half your ranged and siege equipment unusable untill 10-20 minutes into the battle
Whole idea is inspired by vovka's post:
We already have enough trouble with modifiers armor after the fight, which is why you are forced to clean up more than 100 items with different modifiers. It would be nice to combine your stupid idea and a stupid strat system to another over a stupid system - and prohibit the use of weapons looted from the battlefield until to be fixed for the % of its value. Until then, it will be stored in crates.
If you allow repair only from character's inventory, and prevent while fief under siedge - its eliminate this stupid cases where the besiegers are sponsoring fiefs with their own weapons after of imminent defeat against the garrison at 3+k troops because of another stupid system
Figured it would be easily overlooked, and a great idea deserves some attention.