I just noticed The Order of Ancient members carrying Yggdrasil symbol with them, like Templars Shay Patrick Cormac and Juhani Otso Berg. I wonder if there is deeper meaning or connection. :
Assassin's Creed Confessions — Charles Dorian's death in Rogue killed me. Passing...
Arno kills Shay Cormac [AC Unity: Mods] - YouTube
What connection does Assassin Creed 3 have with Rogue? - Quora