It’s essentially making a magic item with the fluff that you are redeeming an item. It’s weird that you need to cast dispel magic to suppress the magic because I don’t think doing that suppresses it for 8hours.
Consecrate dispels desecrate and lasts for hours. That seems more appropriate than dispel magic. shrug
But yeah, you can’t have a warrior ‘teach’ an evil item to be good. You have to reforge it.