So I've been thinking about what makes a good title for a mage. These are what I've observed from trying to think of good title with Pufferfish and Tristan. They're not hard rules, and I'm not going to object to anyone who ignores them completely. :)
1) Titles should be between 2 and 4 syllables long.
Anything longer and it'll be difficult to remember or pronounce.
Any shorter and you'll probably run into someone with the same name ("oh, so you're Master Stone as well, are you?"), so to be special you want at least two syllables.
2a) Titles should have a variety of vowels.
Makes them sound nicer. One of Rupert's prospective ones was "Stormsworn", which didn't sound as neat as another one he suggested ("Skysworn") because both syllables have the same mid-low back vowel in them. This may just be an aesthetic concern of mine - I tend to pay attention to these things because I'm a phonetics geek.
2b) Titles should not have too many consonants grouped together.
This could be more easily but less clearly summarised as "should be pronounceable without tripping over them". The more easily people can pronounce your journeyman title, the more likely they will be to use it.
2c) Generally, titles should be easy to pronounce without unintentional embarrassment.
Of course, if you want to have a title that people mispronounce all the time because your character is from another country, for example, go ahead - it'd be quite fun. But if not, try to pick something made up of real words that people can guess how to pronounce and not be far wrong.
3) Titles should not make people twitch OC.
Despite it being a fairly cool title for an air mage, "Skywalker" would have far too many OC connotations for players for it to be a good choice.
(This is particularly amusing as I eventually picked a title for Mary that I thought wouldn't be a problem - 'Voidwalker' - only to have Inquisitor wince when I told him IC because it's the name of one of the warlock pets in World of Warcraft.)