The Mechanics of Spell Casting

[Wolfandre]

If you watch the animations for the spells, you can see the aether drawing into the focus (my sword, as a paladin, which is interesting for being in no way natural) and then the caster physically hurls the aether out, letting it assume its spell form as it flies.

It could be that one doesn't really need a focus to use magic, it just helps (stat bonuses). Therefore, really anything could be used to focus it, including man-made weapons.

So, in a way, the Armoury system doesn't really do much of anything for our spellcasting other than allow us to mechanically access our spells in the game.