The item editor does not create items; you need to have the item first. Check your inventory before leaving Divinity and make a note of the name of the item you want to edit (and maybe some of the stats, so you can tell the difference between similarly named items). The Well Made Skull Cap you edited could have been in a chest somewhere, etc.
For the random stats; each class of item has a certain range of stats it can have. Even potentially powerful items can end up with very crappy stats, but crappy items are not going to get a great deal better if you were to re-load repeatedly.
If you quick save before running your mouse over an item/chest/merchant or hitting the alt key, you can identify the item or trade with the merchant, then quick load to get different stats or inventory. This can be done repeatedly to get the best stats or specific bonuses on an item (save after finding good candidates) or looking for specific items (such as spell books or charms) from merchants. Don't waste too much time with this, though, it really isn't necessary to get the best possible equipment.
