hahahahaha the blades were originally dragon slayers from akavir, once they were on the verge of wiping the dragons out on akavir some escaped to tamriel, and the "blades" followed them. unfortunately now they are mostly worthless and deserve death at the hands(or claws) of mudcrabs.
yes, it does fit, but only just

and all the dragons (Every last one of them but the ka po'tun king who i believe was not a dragon at the time) were killed on akavir, none escaped lore-wise