User blog comment:IamJakuhoRaikoben/Sorcerer Magazine, Issue 17: May 2013/@comment-4829046-20130605090234/@comment-5840892-20130606025704

That's the one he mentioned, the Sword Forged in Darkness. It grants great power to whoever weilds it, but it utterly corrupts and eventually destroys them. It is a blade that can destroy the world as we know it, but in the hands of one who cannot be corrupted, it could do much good. (In my opinion anyway.)

I guess the other one I was told was the Sword Forged for Justice (or Forged in Light). It fits the bill for what I was describing.