This skill does not appear to work. I have a few corruptions across my inventory (I am reasonably certain they are not negative Krongs), and the skill does not appear to address these artifacts in any way. On the plus side, also no cooldown or debuff, but on the minus side: uncleansable corruptions! Having my gear all tweaked out irreparably is annoying!
Was doing that and consistently getting no result. Now I am occasionally getting the debuff, but not undoing the negative stats of the item.