After you get the battle tower, about half way through the game, you will be able to raise the level cap of most skills (Lockpick and Mana Efficiency only have 5 levels, for example, so there are no upgrades for them). There are a couple stages for the upgrades, for increasing amounts of gold (the first can bump the level cap up to 10, the second up to 13, or so, depending on the skill).
Wow, I didn't know that. I was planning for 5 points in most of the skills I wanted to take. Now I may need to rethink some things if some of those skills can go higher.
