The Transcendent Blacksmith's Regression

After awakening as a blacksmith, I spent my entire life immersed in crafting, solely to protect humanity. But humanity fell—not to the Tower, but to traitors. The weapons I had forged with all my heart and soul were reduced to tools for those traitors. Heroes fell to the enemies pouring out from the collapsed Tower. Only as I reached the threshold of death did a regret surface. "If only I had believed in my own potential and climbed the Tower myself." "Could I have created a different ending than this?" As I was dying, drowning in a sea of surging regret and lingering attachment, it was none other than a mysterious core of my own making that raised me up. [Congratulations. You have...