Also, about a Guardian's immunity to magic, exactly what are they able to do?

For example, if me and Sekai were happened upon by Guardians, would they be invulnerable to her metal arm? Would it fall apart if she hit them with it?
and my barriers, if they attacked me, would it cut through my barriers like they were nothing?

Or is it just that they're immune to things like fireballs and curses?

- In other news, Saltwater Thief, do you think Alaric and Emil would know each other? Since they are both from the Tower, and are of similar age.