To reach a certain grade in the Mages’ Guild, you have to pass a theoretical and a practical test in several disciplines to prove you are capable of using and managing magic power of that level. Grade 4 is pretty average for an older mage in some higher position, but not exceptionally good. Katharina also being 4th grade means she is actually remarkably capable for her age and experience.

Still, she calls Coumi “Master”, because that’s how you call the leader of a guild house.

Updated on 2017-10-28: I still think Alistair is a great name. When I hear it I always think of the grey warden Alistair from Dragon Age, and the malkavian Alistair Grout from Vampire: Bloodlines …

↓ Transcript
<Somewhere else in the city, Katharina enters the building of the local Mages' Guild>
Katharina: ... Hello?
Master Coumi: Ah ... Miss Grauch, I presume?
<They both shake hands>
Katharina: That's right, Master ... ?
Master Coumi: Alistair Coumi, 4th grade and leader of the local mages' tower. Pleased to meet you.
Katharina: Thank you very much, Master Coumi. Katharina Arkadia Grauch, likewise 4th grade and sent here from Beckstown by the guild on behalf of your inquiry ...
Master Coumi: Great, great ... did you have trouble finding our home here? I hope your journey down here was a pleasant one.
Katharina: Erm, the journey was a bit ... exhausting, but I'm fine. But I must say that I'm used to the mages' tower being a bit more ... prominent in a cities appearance. I had to ask a few ... people for the way down here ...
Master Coumi: Ah, yes, I know that we usually tend to make ourselves a big sight in most cities we live in ... but here in the south, between byzarian city-states and near the great wall, we're a bit ... outside our influence, if you know what I mean. Not everyone here respects mages as you might be used to ...
Katharina: <sighs> Yes, I ... already noticed.