Your arsenal details the weapons which you have in your possession.
For example: wooden Bow 10 20 8
Mean that you have 10 wooden bows making 20 damages attack (when it is you who attack) and 8 in defence (when a Lord attacks you).
Quite as the techniques of siege or production, it is possible for you to resell the complete stock of the same weapon, against 80 % of its price of its new cost price.