Could you elaborate how, only way I know how is by secondary skill trainers?
At the moment I'm level 7 and raking a lot of money in the Monster Bowl Arena of the second town.
kmonster points out some of the ways to raise stats in his post, below the spoiler warning. Those are the easiest ways to raise stats, but there is another way too:
*** Spoiler alert ***
As you explore the world, you may come across fragments of messages. Write these down, and when you've assembled and decoded the messages you'll find instructions for another way to raise your stats.
**** End spoilers ***