Hey, sorry I didn't read this but the title caught my eye. I think you mean Cormorant, not concordant. The Cormorant were a group, who still exist today, that fought a forgotten enemy long ago. Notable members include Eriana-3 and Commander Zavala. The seal can be found on Dust Walker, Makeshift Scarf, Seal of the Twin Eagle, and Honour of the Cormorant.
Not to be nitpicky, it's just I'm trying to learn everything I can about the Cormorant right now. I used to think they were the first legion of exo, but as I said Zavala wears the seal on his chest so that opened it up. I still believe, thanks to the deep stone crypt grimoire, that they were originally exo.
I'm pretty sure it's Concordant. In the grimoire, Concordant was a radical faction in the early days of the City. Though the Cormorant faction is very interesting
Dug a little deeper, you're absolutely correct it's Concordat. They were led by Lysander, clearly in your story, and were disbanded by the consensus for being too extreme. They then continued their own crusade as the FWC joined the consensus
Oh awesome! Yeah, I didn't have time to find a credible source because I'm somewhat busy at the moment, but yeah, Concordat. And I've been spelling it wrong the whole time LOL