Once you learn a toolbar, it just becomes visual and muscle memory. Not unlike using hotkeys to access something hidden under a couple layers of menus.
Sure, but that's very different from "feature discovery". I totally get this with the floppy-disk icon (which is, ironically enough, now a terrible visual metaphor for persisting to local storage outside of cultural context), but I have no clue what "up arrow on top of down arrow" means, nor what the ¶ icon would do—start a new paragraph? Select the current paragraph? Open some kind of paragraph outline?
Granted, I don't use windows so it's entirely possible I'm just showing my ass here.
The toolbar buttons all have hover text to ease the learning, ¶ is "Show All Characters" where "characters" mean stuff like Carriage Return and whitespace. Microsoft Word users are probably familiar with this meaning.
I have no idea what "up arrow on top of down arrow" is though, because I don't have that button.
