# of their own free will

"by their own choice." This means that they will chose to follow the king.

# on the day of your power

"on the day that you lead your armies into battle"

# from the womb of the dawn ... like the dew

"in the morning ... like the dew" 

# from the womb of the dawn your youth will be to you like the dew

"each morning you will be filled with youthful strength to sustain you just like each morning the dew appears to water and sustain the earth"