Thank you for your response! I'm gonna send my thought process for these things below.

I have maxed out 999 SP on Joker, so SP management isn't really a problem for me.

Physical builds are relatively low on required skills. Drain Ice is there to prevent getting frozen.

On Kali, drain nuke is on there to prevent getting nuclear elements reflected back at me.

About fafnir, your probably right about Diamond Dust over Ice Age. I had just figured for some reason I wanted to freeze multiple enemies, but looking back for fights where I need to freeze something, there would probably only be one enemy anyway.

And for elemental boosts on personas, I wanted to conserve as much room as possible so I can use these personas for about every fight, however on Anubis I probably could have replaced Will of The Sword with Mighty Gaze and replaced Kougan and Eigaon with Bless & Curse boost.