Oden was smashing the bats with his so-called green power. The so-called green power is estimated to be at king level, according to Oden as Syra was a king when she gave him her nail. Even she wouldn't have thought that Oden could use the power this often.
Oden has been using this power to do every task possible in his life. Relying on someone else power means getting dependent on something. Oden didn't know but Ham knew that his king power will be depleted soon if he uses it for every single task.
If this goes on the day his king's power is depleted, he will lose it all. Everything he has.
Oden does not the value of power, he has got a scary potential body and king power without any struggle. He has no value in these things.
Ham repeated:
'Those are your secret moves, if you are dependent on them, you can never grow.'
Oden deactivated his power, took out a knife that he just brought from the market. There was nothing special about the knife, but he can kill the bats with it.
