Thing is that spell levels are pretty different across some classes.
Furthermore, Knight isn't really a noble title of the Lord -> etc. line, since you can become Lord without having been a knight and can be a knight all your life without ever becoming a Lord. Knight is the odd one out that is based on deeds instead of birth like the other titles.
And I would really prefer to make a proper difference between researchers, war mages and crafters. You've said yourself that you want this to create little boxes for people to put casters in and speaking with Leila over the same things you spoke with Vee about is not going to go over that well. These two are vastly different aside from their respective power, much like how Stannis, Roose Bolton, Petyr Baelish, Gregor Clegane and Loras Tyrell are nothing alike.
Edit: Lastly, I want to give people a clean way to gauge how screwed they are when they annoy someone. Insulting the Grand Enchantress is probably not nearly as hazardous as getting on the High Warlocks nerves.