Cue the Dark Souls boss music.
That's what I thought at first but it looks like we're headed towards an Alien re-enactment.
This is me just guessing here, but I wonder if it is possible that their "dick power level" are affected by their "purity and innocence".
An and that elf lady from before both have ridiculously huge junks, and they are like children with how they think of sexuality.
Just a detail I noticed.
My own take is the level of sexual denial, that aligns itself with the saintess, who was not pure, but denied herself being a freak in the sheets.
Ultimately this is moot as the only true reason for the size of each dong is what the author thinks is funny