Am I missing a way to make custom attacks show up at the top with all my other "Actions" like normal weapon attacks, instead of near the bottom of the actions page? I'm trying to make a custom attack for Shadow Blade but I can only make it show up in the Other category, but it would be a lot more convenient to have it show up along with all my other attacks.

It depends on the activation type. I assume the Shadow Blade attack counts as an action, so set the activation type as action. It will show up in Actions, not Other.

Sweet, that was it.

One more, related thing. Is there any way to populate the notes section of a custom attack? Shadow Blade should have all the same notes a dagger, namely in my case: "Simple, Finesse, Light, Thrown, Range (20/60), Booming Blade: 1d8". But I don't see a way to add that.

I would put those in Snippet.

Quote from filcat >>

I would put those in Snippet.

Currently anything you type in the Snippet box does not show up in the notes section.

Yeah, I know, as of now, there isn't a way to custom the notes section of an attack.

Quote from filcat >>

It depends on the activation type. I assume the Shadow Blade attack counts as an action, so set the activation type as action. It will show up in Actions, not Other.

Shadow Blade actually creates a temporary magic weapon that you can wield normally (as opposed to similar spells like Flame Blade or Spiritual Weapon which create weapon-like effects that can only be used with ad-hoc actions or bonus actions.)

That said, you could create a homebrew magic item with all the right properties for it.