Help Making Weapons upgradable past +10 using Yapped-Rune-Bear

[XelumTheInfinite]

So the situation is this:

I can easily use yapped to make certain weapons upgradable up to +15 but not only is there not an increase in the weapons' stat values, they seem to revert back to the values they had from before they were upgraded at all, and I also have no knowledge on how to indicate what materials and their amounts would be required for the upgrades. I'm not doing this for the sake of making a mod, I'm just trying to take advantage of yapped for the purpose of making my favorite weapons stronger. Unfortunately some of my favorites have had that previously mentioned reduction in stat values when I attempted to upgrade them thinking that stat values are increasing when they are in fact reverted and unable to increase. I hope I haven't ruined them and become left without a way to fix what I jacked up. I could really use the help of someone who knows how to use Yapped Rune Bear better than I do!