When crafting there is two types of items you can craft. The first is the most common and that is a fixed advantages with a fixed rarity. The second type is the focus of the article, the fully customizable enhancement. This type is recognizable in the Development Tab of the Crafting table by the enhancement being in Italics. Once selected the interface changes to show a Sliding bar labeled "Quality", followed by two drop down lists labeled "Minor" and "Major". Note not all will have a "Major" listed as some are "Minor" only.