Currently there was only three ways for me to power up. The first was to Ascend. The 2nd was to draw the power of my girls into {Limitless}. And third was to improve the power of my weapons.
I have long decided to not Ascend haphazardly. The ability to create a new {fate} when I was overwhelmed was something I wanted to keep as a trump card. I already had a near infinite supply of souls from my aggressive farming tendencies.
The 2nd was naturally to gain the improve abilities of my girls. As they were part of my power, each time they grew stronger I did too. Although I did feel a bit guilty that they were my level wasn't keeping up with them.
As demonstrated by my recent duel with the Sirens, version 4 of {Limitless} was OP! Combined with {Day by Day} and [Maestro] I was able to fight like an entire squad of Reapers. Even against all seven of the girls, I somehow triumphed.