And what are we supposed to do with this, Dean? Give it a booster shot?
The Sword of Bruncvik, like Excalibur and St. George's sword, is a weapon capable of killing dragons due to being forged from the blood of a dragon. Reportedly only 5 or 6 such swords remain in existence.
Dr. Visyak, who owned the Sword of Bruncvik, told Dean that finding it took two decades, countless hours, and some really bad sex with an eastern European ambassador. She described it as the love of her life.
Upon Bobby's advice, Dean visited Dr. Visyak on how to deal with dragons; specifically how to kill one. The doctor replied that dragons can only be killed with a blade that was forged in their kin's own blood. Dean noted the conundrum: something like that can only be made by killing a dragon, which cannot be done without such a blade at one's disposal in the first place. Fortunately, Visyak happens to have one in her possession. The sword is bound to a stone to protect it, and Dr. Visyak told Dean that, according to the lore, only a knight ready to slay a dragon can pull the sword from the stone. Dean was unable to extract the sword so he resorted to plastic explosives, which, although freed the sword from the stone, also broke the sword in half. Dr. Visyak gave a horrified look at the broken, priceless sword.
Sam: And what are we supposed to do with this, Dean? Give it a booster shot? Dean: It's what we got. All right? We're just gonna have to get a little closer. That's all. Where are we on the caves?
In Mythology, Bruncvik is a hero from Czech legends who left his wife to go pursue adventures in foreign lands. Along the way he acquired a magical sword that had the ability of chopping of heads with a simple command: "Blade, heads off". Later he encounters a white lion battling a nine-headed monster and he helps slay the monster. He and the lion become friends and travel together.
In Bobby Singer's Guide to Hunting, Dr. Visyak wrote that the dragon-killing swords were forged with the blood of Hypolyes, a dragon who willingly sacrificed his life to help Eve, who realized her dragons were so powerful that they could destroy the other children she created.