Word of caution about the item editor. when you modify an item you are modifying all items in that class. For example u modify an iron long sword you also modify all the long swords in the game(this includes the ones your enemies are using) I just had to go back and try to remodify all the items i changed to approximate the original values. You also cannot place fractions of a number into the values so i was stuck with whole numbers. so be cautious with your value changes. Just a heads up
How can people not know this, otherwise months would have to be taken to make individual creatures with different swords without it being an actual "sword"
Indeed, it seems all the trainer does is modifying a base value for a weapon class.
However in my experience the modified values do not save. The items revert to their original value after restarting the game and trainer. Is it supposed to be this way?
yes. right now all you are doing is telling the game you have such, it does not modify any files only your current game.