What exactly is the Black Beast, what are the Crests, and what are their role in both narrative and gameplay?
Some little brainstorms I had regarding the possibilties:
-Crests can possibly be basically glorified brands(a la Fell Brand, Exalt brand). In the trailer, we see Edelgard magically projecting her crest during the Black Eagle introduction. As each student is likely a noble, it would be plausible if each student had their own unique crest.
-Alternatively, since the Black Beast lists it's weapon as a Crest Stone, perhaps they are simply family heirlooms for each noble.
-the Crest Stones caught my eye being, well, stones, a la BEASTSTONES. This is probably reading too hard in, but knowing how Sylvain and the Crest that Black Beast wields, as well as the pretty much guarantee d fact the church is probably evil, could the Church had done some horrific magic hoo-ha, and corrupted your classmates at some point in the story, turning them horrific Black Beasts? That would make the choice of House all the more important, as you're probably going to have to kill other students you couldve saved otherwise.
-Alternatively, if the Crests end up being physical items/heirlooms, the church/other possible enemy could simply steal them, and turn the stones alone into Beasts, or simply power sources for the Beasts. Either way, we know the Crests will inevitably be used against the player.
-The Black Beast takes up 4 tiles. In the event we do get beast units, I hope they will be also larger units on the map like the Black Beasts. That would make them much more interesting as units imo, as in the FatesWakening games they basically acted like regular infantry, with the stones basically being glorified melee weapons.