Adam Heine, you've played The Banner Saga right? I like how they handled adding Willpower to attacks, it was just a simple button click, a slider might involve more clicks - which isn't really a good thing.
I'm kind of in love with Banner Saga, yes. It was that game, in particular, that made me think requiring a "confirm" for an attack could work without being annoying (in turn-based, at least -- I'd never have tried something like this in a twitch combat system, autopause or not). With Banner Saga, I never once was annoyed with, or even noticed, being required to click twice (and there were a few misclicks where I was grateful for it!).
In general, if you're not applying Effort (or applying whatever Effort you get for free because of Edge), you click once to choose what you do (default attack, secondary weapon, class ability, etc) and once again to confirm default Effort -- pretty much exactly like Banner Saga, but with the additional option of free Effort/Willpower depending on your character build. If you want to apply additional Effort, you can drag the slider, click the slider (I think; we're still fiddling with the UI), use hot keys, or even use the mousewheel before confirming the attack.
One of the main reasons we did it this way is because the Numenera system is something most players are unfamiliar with. Effort is such a key part of that system that we wanted to make sure it was right in front of players. When Numenera becomes as well-known as D&D mechanics, then maybe we can hide it
.
We
may implement a game option to turn off the "confirm" -- possibly requiring the player to right-click or something to apply Effort to an attack -- but that will require some extra design work and so is a lower priority than getting the default UI-and-options working and fun. When that's done, then we can talk about advanced options
.