Thanks!
So, if you're trying to stat out a character that starts out as an apprentice wizard and progresses to Kemmler-level badass, how would you go about that without inflating the numbers too much?
Slowly. Pick a specialty for them, and focus their upgrades on that -- with the acceptance that some things are just going to end up being weaknesses for the character. Which is not a bad thing! Weaknesses make for great drama and chances for character growth, either by overcoming those weaknesses (which usually means getting them up to adequate levels, not making them the best at it) or accepting them and compensating in creative ways.
So if your Swording Wizard has to make Investigation her dump stat so that her combat stats are adequate-to-high? Perfect opportunity to expand her cast with, say, a computer hacker character that can look into the things the wizard can't, or a rival private eye.
Or the wizard is forced to talk to demons and pixies and such.
No protagonist is an island -- and you can have a lot of fun teaching them that the hard way.
I mean, look at Harry Dresden. When we first meet him, he's basically got two big tricks over his opponents -- a hefty magic punch and he's a keen investigator. As the books go by, he's confronted with his deficiencies (usually in the forms of getting his arse kicked or finding a dead body he could've saved), and then he works to remedy that.
By the time of, say, the short story Heorot, Harry can win a fist fight with a couple thugs that Murphy probably would've wiped the floor with. Which is to say Harry accounted for his weakness and sought to bolster it, but he didn't get to a level beyond what others can do.
All that said, if they're a protagonist, I wouldn't let them get near Kemmler's level, because Kemmler is more of a plot device than a character, someone who can effectively "cheat" the normal skill distribution.