I worked with shadow on it, but if I remember correctly this helped clear things up a lot in the price.<br/><br/>" In addition to the masterwork levels, any weapon or armor can gain craftsmanship bonuses up to twice their masterwork level. These bonuses can be applied during crafting or afterwards with a 10% price increase with the exception of the AC and Damage increases. Each bonus cost 1000gp base cost.<br/><br/>No item can have more than 1 craftsmanship bonus of the same name at a time. Additionally, if a bonus has different ranks as indicated by roman numerals, you may apply a higher rank over the lower rank by only paying the difference in cost."<br/><br/>There is no magic in this game, so rather than an item having to be magical before an effect can be present, it needs to be adequately crafted.  Think if the craftsmanshift as almost like attachments.  They can be added after creation, but masterwork is only when the weapon is made.  Therefore you do not need an empty plus 1 craftsmanship to have an effect, so keen adds 1000 plus the masterwork price, plus the weapon.