I see a lot of complaints about early classes feeling weak (or useless) compares to later ranks and I whole agree.
Easiest fix? Like every other game with a clue, have every skill have a flat damage and then do additional damage based off of the appropriate stat.
For example: Blessing (priest skill) could remain unchanged as a skill, but remove the flat bonus for investing in the upgrade and have it add 1% spirit per rank (50% at Max).
This prevents the skills from being too powerful initially while keeping them relative late game.
Of course for other skills you would want to apply the correct stats, such as strength, attack power, int , magic attack, etc.
With the ability to invest both skills points and money to improve skills just adding proper ratios will keep skills in balance both early and late game.
Final and somewhat off topic note. Adding or moving classes to earlier tiers would encourage more player diversity and unique gameplay. Would really appreciate more than 2.5 choices at second rank. And if everything scales and remains relative it wouldn’t hurt to redistribute the ranks.