Looks at this beauty again (meaning the sword, not the Blade).

—I see, so now we know who to suspect if anything happens, heh-heh... —weighing the upgraded sword in his hand, he made a few test swings, noting that the steel had become even lighter than before. —Thank you, I don't even know how to thank you, but... Doesn't this defy all the laws of blacksmithing? They literally confirmed to me at Upgrade today that it's impossible. How did you do it? I hope you didn't sell your soul to some celestial blacksmithing forces?