For example, when he was at the first mortal coil, he didn't have internal energy, so he could only use physical arrows with the golden bow.
This changed when he advanced to the second mortal coil. Once he gained internal energy, he could condense energy arrows with his internal energy and didn't need to carry physical arrows around.
What he could use the golden bow to do changed again when he advanced to the third mortal coil. At that point, he gained a divine sense and could use it to control the energy arrows to give them a limited homing capability within the range of his divine sense.
In all of these cases, the upper limits of the power of the golden bow remained the same. What changed was his utilization of the golden bow.
But now that he had advanced to the fourth mortal coil, both the utilization of the golden bow and its upper limits remained the same. If he tries to force the golden bow to produce more power by inputting more energy into it, he can break it.
