Interesting choice of element build you decided for Horus; definitely a first for me. Most of the videos I see have him built for Bless type damage. I decided to build him as a Nuclear type because of theme and aesthetics; his eyes are the sun and moon, he is the Egyptian Sun god so it seems only fitting he would have attacks like Atomic and Cosmic Flare, right? To each their own but your videos and P5R content are amazing as always; keep up the good work.
I love horus as a God, as hus story is awesome. Essentially Horus was a bird man and his angry uncle Seth (the dragon thing) wanted to kill Horus. Horus got hidden underwater from Seth so he wouldn't die, and didn't drown. As soon as i saw horus was in this game I immediately wanted him, as his story is quite unique, and I like birds.
If you want to save sp bargain bolts is good. Mighty Gaze works on multy hit skills only so you can change Thunder Reign for something else. Mighty Gaze gives the same damage boost as Will of the Sword but Will of the sword works on any skill you use.
You can get those especific skills when you do a network fusion, it can be any Persona so for example I got magic ability in a Sandalphon, you can get it on a Chi You, everyone gets those skills on a different Persona, but only if you create them with the Network Fusion system.