Warning: contains spoilers for King in Black #5 and Venom #34!
Fans knew that no normal weapon was capable of striking down the King in Black, but no-one was expecting the incredible battle ax that Venom forged to slay the God of the Symbiotes in the closing chapter of Donny Cates and Ryan Stegman's epic clash between good and evil. Escaping Knull's God Hive just in time to bond with the Enigma Force, Eddie Brock and his symbiote partner were able to seize control of Thor's hammer Mjolnir and the Silver Surfer's board, merging them into a mighty battle ax capable of tearing Knull to shreds.
While combining the two weapons was a huge surprise this issue, both had already shown they were capable of holding their own against Knull. Silver Surfer: Black showed the Surfer shift 'Toomie' (a nickname given to the board by the Surfer's beloved Dawn Greenwood, who misunderstood his characteristic "To me, my board!") into a sword in battle with Knull, while King in Black #3 saw Thor relieve Knull of his jaw with his hammer, Mjolnir.
King in Black #5 sees the weapons merge, as Eddie Brock harnesses the Uni-Power (an aspect of the sentient Enigma Force), becoming the latest version of the hero previously known as Captain Universe. An ancient enemy of the King in Black, the Enigma Force was brought to Earth by the Silver Surfer, empowering Brock at a point where he'd apparently already been killed by Knull. The truth was somewhat more complex, as Eddie still existed as a codex within Knull's vast God Hive. With his Venom symbiote still in the material world, Brock was able to fight his way back to life, offering the Enigma Force a suitable host, and bringing the Uni-Power into play. After striking blow after blow against Knull, Venom forced him into the heart of the sun, only then allowing the nervous Thor and Silver Surfer to reclaim their weapons.
With the Enigma Force ax now unmade, Venom's weapon had only a brief time as the most powerful in the Marvel Universe, but its might can't be understated. Harnessing the Odinforce within Thor's hammer and the Power Cosmic imbued into the Silver Surfer's board, Venom's ax commanded two of the most powerful forces in Marvel Comics, even before adding the might of Uni-Power. Venom effortlessly slices off the head of one of the King in Black's possessed Celestials, a historic feat that was previously used to establish just how dangerous Knull was to Earth. The only caveat is that Venom may not have been able to wield the ax on any other day - Thor has recently been struggling with his weapon's enchantment, which is supposed to only allow the worthy to lift Mjolnir. It's unclear whether Venom benefited from this or whether the Enigma Force is just so all-encompassing that it forwent this restriction.
Is the Enigma Force ax gone for good? In comics, the answer is always no, but the very particular ingredients - Mjolnir, the Silver Surfer's board, and the Uni-Power - are unlikely to come together again, especially in Venom or Eddie Brock's hands. A more likely candidate would be the Fallen One - the disgraced, Mjolnir-wielding Silver Surfer of the potential future where Thanos is triumphant - or perhaps the next host of the Enigma Force, whoever they may be.
Knull was one of Marvel's most powerful villains to date, and so it's appropriate that Venom forged the comics' most powerful weapon to defeat him. Having taken the King in Black's title for himself, and been warned that Knull's primordial darkness lives on within his son, Eddie Brock and the Venom symbiote have some huge responsibilities waiting for them in the future. Hopefully life will be made a little easier by the fact that Earth's protectors now know exactly what Venom can do when the chips are down.