I have a theory in regards to Xenoblade and X.
Basically, with the introduction of using giant robots, I find it ironic that the previous game took place on and inside two gigantic robot worlds, and now the humans are using them in battle and transportation.
I believe, that "X" is a sequel to Xenoblade Chronicles, which takes place in a future where the Bionis and Mechonis are essentially remembered through the usage of said robots. They are used in battle to resemble the strength of the storied titans.
That's where references to a hero and his blade would come into play. The Monado is a legendary blade according to Xenoblade's lore, so if "X" is a sequel in the same world, then it doesn't seem all that ridiculous for it to make an appearance or get referenced.
Some of the areas take on a similar appearance to areas from Xenoblade chronicles, and my theory branches here as well. There is an area with a darker image to it, with flying creatures and such. I believe that this would be the part of the world in which the Mechonis would have existed.
It could be assumed that after the events of Xenoblade, the world of those people would have flourished with commerce, hence why there are great cities instead of what were once colonies.
They're minor details, but I think they could work.