I saw it discussed in another forum, but essentially it would be a great idea (for me at least) because it is easy to make a mistake when levelling up a commander; i don't know yet what will be the best way, or how will i use him better in the future.
it's just too obscure right now to let me know where to guide his levelling.
right now, for example it seems useless to invest in magic resistance, but what about tomorrow?
of course it should be limited, or else i would keep managing my bonus on the spot, it doesn't seem right. one way of limitation is a cooldown, as it was said, or an EXP price: that way you only reset your commander when you understand you made a mistake; and not to adapt yourself to a situation.
in case you screwed up: this is different, i just misclicked.
for that it would be nice to have the posibility to undo 1 or 2 levels. of course it's hard to control and such. another one that seem VEEERY dangerous is to be able to undo the leveling until the commander is used in any possible action