You need to set the text of Inventory_Item_Text to the weapon's description each time the player selects an item. In other words, when the player selects the item, do something like...
PHP Code:
Inventory_Item_Text.text = weapon.description;
where
weapon is a weapon object (e.g. from
findWeapon as above).
Additionally, the description needs to be a flag on the weapon object, so use
this.description inside the weapon like Gunderak showed above.