Superman & Lois has managed to invent the Arrowverse version of Marvel's Mjölnir through John Henry Irons. One of the big twists in Superman & Lois season 1 was the unexpected arrival of a certain DC superhero. After having posed as Captain Lex Luthor from another Earth, it turned out that Wolé Parks had actually been John Henry Irons, better known to DC fans as Steel, the entire time. Superman & Lois became the first DC live-action property to use Steel since the not-so-memorable Steel film from 1997, starring Shaquille O'Neal.
While John's arrival in the Arrowverse was a surprise, it has allowed another beloved Superman ally to come to life. As the first season is ramping up the storyline with Morgan Edge, John is now working with Superman and not against him as he was initially. In Superman & Lois episode 12, "Through the Valley of Death," John assisted Lois and Sam Lane in trying to stop Superman as Zod's mind had taken over his body. To do so, John had to use his Steel armor and kinetic hammer to go toe-to-toe with Superman. Even though it was probably not an intentional nod, John's hammer had a similar function as Thor's hammer, Mjölnir, in the Marvel universe.
During their showdown, Zod managed to get the upper hand on John before the latter was able to call his hammer back to him. The last time Superman got hit by the hammer was in "Man of Steel," where John weakened Clark through his solar flare lights. It turns out that even under a yellow sun, Clark can still get hurt by John's weapon. Even though this is not a direct reference to Mjölnir, Superman & Lois is the first DC live-action show to feature a similar weapon like Thor's hammer, a weapon that can return to John when he calls it. The only difference between Mjölnir and John's hammer is that the former is enchanted while the Arrowverse weapon was made with advanced technology from another Earth.
The fact that John's hammer can still hurt a Kryptonian without using Kryptonite or solar flare lights makes Steel a formidable opponent. While Superman & Lois have featured the hammer in action a few times already, there are still many functions that Arrowverse viewers have yet to see. In the comics, John's kinetic hammer is capable of producing electromagnetic effects for various situations. If John wants to, he can use the hammer as an EMP to shut down electronic devices near him. Even though it's not exactly like Mjölnir, John's hammer does have another similarity to Thor's weapon. If Steel enables the hammer's ability to tune itself to Earth's magnetic field, it becomes impossible to lift or budge it.
While one can only wield Mjölnir if they're deemed worthy, Steel's hammer can be lifted by anyone if John hasn't magnetically locked it. While John's hammer has so far only shown how it can absorb kinetic energy, that doesn't mean his weapon won't demonstrate the other capabilities in Superman & Lois season 2. It is always possible that his hammer doesn't have those features yet, and it might be something John develops next season. As Superman & Lois progresses further, it will be interesting to see Steel's role on the show, especially in future seasons.