A character's level would indicate how many skill families the character
could know. A level one character could study one parent skill. Later,
after attaining lots of fame, he would progress to level 2, and could pick
up a second skill family.
Older characters that had done lots of things would know more
Characters would have to do stuff to advance
Players would be more likely to specialize than to try to
learn all of the skills
Personally, I don't think narrowing a character's focus is an important goal.
In Olympia today, how many different skills does the average unit have? My
guess is it's somewhere between 0.5 and 1.5 different skills.
Also, if we're going to a COMPANION system, or even just adding RUINS where only
single-man units can enter, then I think units will need two or three skills
at a time - most will have combat and a second skill, where that skill is one of
Military Leadership, Observation, Stealth, Archery.
Finally, I'd personally encourage people to have more balanced characters - it
adds a little personality and variety. Heck, I'd personally add some synergy
between different skills - ie. it requires levels in more than one skill family
to get a subskill. Assassination is Stealth and Combat, Pickpocketing is
Stealth and Observation, Create Dragonslayer is Weaponsmithing and General