Skills do not improve after level 4?

[Arobinson]

I have been noticing that it seems that level 5 is the same as level 4 for skills. For example, my warlock has level 5 mage's claw with MP recovery of 4. Level 4 also has an MP recovery of 4. I think I have seen this with other classes as well. Is there a bug that skills > 4 don't actually improve the character?

[ursuskuma]

http://global.com2us.com/forum/showthread.php?t=172575
For mercenaries,Yes, it's not increase anything. But if you use skill book on Kiyan,it improved.