Lucasfilm's Dave Filoni and Jon Favreau explain the Armorer's role in The Mandalorian, and why she is able to command Din Djarin even though he possesses the Darksaber. Played by Emily Swallow, the Armorer is one of the most important figures in Mandalorian society. Still, viewers were rather surprised when the Armorer declared Din Djarin an apostate in The Book of Boba Fett. In doing so, she seemed to be claiming a position of authority over all Mandalore, given she was speaking to the man who possessed the Darksaber - the rightful ruler of all Mandalorians.
Screen Rant had an opportunity to speak to Lucasfilm's Dave Filoni and Jon Favreau ahead of The Mandalorian season 3, and they explained the relationship between the Armorer and the warrior who wields the Darksaber.
"Dave Filoni: She's kind of the lore keeper of the group. She's the person that knowledge is passed on through. We were talking about how there's probably an Armorer that precedes this armorer, and it goes back through time. The songs of eons passed. Mando is a warrior, and the warrior carries the sword. The shaman has a different role, and the wizard has a different role. Merlin guides Arthur to find Excalibur; Merlin doesn't wield Excalibur.
Jon Favreau: The High Priest and the King or are separate in the Bible. So, we're going back. We're drawing from myths and archetypes in myths as George [Lucas] has done and instructed.
Like Merlin, then, the Armorer is the one who initiates the hero's quest. In this case, she is the one who told Din Djarin to return to Mandalore in search of redemption - the one responsible for kicking off The Mandalorian season 3.
The Relationship Between Din Djarin & The Armorer Is Based On Classic Archetypes
Many elements of Mandalorian history and culture have been inspired by historical Judaism, so Favreau's reference to the King and the High Priest in the Old Testament is particularly interesting. He is essentially indicating a division of power and authority in Mandalorian culture, between the physical and temporal (the warrior wielding the Darksaber) and the spiritual (the Armorer). It is not necessarily that one is superior to the other; rather, they must act together in concert, or they cannot act at all.
This would explain why Bo-Katan Kryze cannot reclaim the Darksaber. Her initial claim would have been rejected by the Armorer, simply because she was given the Darksaber rather than earning it by combat. She had a second chance, but that was lost when Din Djarin defeated Moff Gideon in her place, and she would presumably now be rejected under lore. Din Djarin, meanwhile, must redeem himself by returning to Mandalore - not only to restore himself to fellowship with the other Mandalorians, but also to rightfully claim the position of ruler of Mandalore.
Mandalorian society has splintered after their homeworld was ravaged by the Empire (paralleling the Jewish diaspora). This naturally leads to the most intriguing question; how the Armorer's role translates across the various different Mandalorian clans. Hopefully The Mandalorian season 3 will make that clear.