Right now, you can attack a fief with an army, lose and thereby load it with extra, often broken gear and immediately assault it with another force, preventing any action being taken in organizing the excess gear unless the defender has the wherewithal to undertake that action in a matter of moments. This wouldn't be an issue, except for the fact that the game cannot handle TOO much gear to choose from- portions of the gear are rendered unable to be selected despite being able to see it.
This issue most often effects ranged units, though it is certainly capable of effecting all units outside of 1h's (which are at the top of the weapons category in game and thus are most readily able to be accessed- this appears to be how it works, and explains why ranged has the toughest time). It's a mechanic which is intentionally being used to grief others, as of now.
I unfortunately have to propose that there be a cooldown window after a fief is attacked so as to avoid this situation. Even 10-30 minutes would suffice, and as something similar to this already exists for field armies it shouldn't be difficult to add.
Alternatively: Allow outgoing transfer of only items RECENTLY added during the 4 hour incoming transfer window given by a follow-up attack. This would allow the selling of broken gear, low amounts, etc and increase enjoyment for ranged and all classes (having to spawn with broken weapons just to allow others to play their class isn't "fun") while keeping locked down any gear, goods, and gold which were not recently added to the fief.