Cool, thanks for the clarifications. And as per the elemental discharge? Seems a bit like a trap due to how long it takes to actually do. Also, going into more details on the Arts themselves, what should I be aiming for? Power Boost seems to be a nice solid pick, but haven't really experimented with others outside of the default spergout combo which sucked.
Trance slash is by far the weakest saxe art, just because it takes so damn long, but is hilarious to use for style points in a triple art style because both demon riot and tempest axe buff its already high damage.
Energy charge is the bread and butter, and was so good that it had to be nerfed going from gen to GU by giving it a significantly longer time to charge up. That being said, it's still fantastic, though primarily at levels 2 and 3, which give you a 10% and 30% affinity boost on top of filling your morph gauge.
Demon riot is the main reason switch axe pairs so well with styles that have multiple arts. Depending on your level, you get a 5%/10%/20% boost to some stat based on your phial (20% extra raw at level 3 if you're using a power phial is insane), and sword attacks don't deplete the morphing gauge for a duration, though it goes down over time, and can't be manually refilled. However, you can use energy charge to bypass this, staying in sword mode in perpetuity if you're aggressive enough, hence the nerf to how often you can spam energy charge. It still works in GU, it just requires skill to pull off now and is no longer free.
Tempest axe is a fun one, but definitely a bit more geared towards late game, as you don't unlock level 1 for a while, and don't unlock subsequent levels until G rank. It improves just about everything in axe mode, and while it's definitely not as strong in my opinion as the demon riot combo, it's still a viable playstyle, and opens a lot of weapons up to being more viable as you're not as desperate for a power phial if you're staying in axe for your dps.