That last point is particularly important because emotion-blocking metal would seemingly help prevent access to the Force, yet Qimir is the only one who ever had the sense to build a Magneto-style helmet to hide from other Force users.
We don’t know what metal he used nor what makes it significant. At a glance, though, it’s something far more sophisticated than what goes into saber hilts.
As usual, the technology of Star Wars makes no sense once you stop and think about it for more than two seconds. Since we generally liked how The Acolyte’s first season ended, we’re going to do what all fans should on this hot summer day: stop complaining about The Acolyte lightsaber colors and pretend the next Rocket Pop popsicle we eat is a laser sword bleeding from one color to the next.