These are two different things.
Sword trust and damage is not a part of your save - it's a part of the module definition. As such, it's out of scope for a savegame editor. But, you should be able to edit item_kinds1.txt for the module directly, and observe the changes next time you load your game. Or, better yet, get the source for the module system for your module, make the necessary changes there, and rebuild the module.
Inventory is a bunch of slots, basically; and each of those slots can be empty, or contain some item. So e.g. adding bread would mean that some previously empty inventory slot is set to contain bread instead. And yes, you can totally do that - look at Troops -> Player in the tree (or whatever other character you want to edit, e.g. your companions). In the property grid, it'll be under "inventory" - "equpped_items" is the stuff you're wearing, and "inventory_items" is everything else. Pick any empty slot - it'll have item_kind_id=-1 - and change it to point to whatever item kind you want there. In a similar vein, you can set hit_points (which for food is the remaining amount), and add modifiers like masterwork to weapons and armor, or spirited to horses.