@angrboda Yeah, they don't make the healing flask an obvious mechanic 'cause you have to buy the first one, so there's no "oh, that's what this does" moment baked into the tutorial. It's one of the few things in that game that I could see polishing up.
I suspect the game designers assumed "everyone's played Dark Souls by now and will know how healing flasks work."
@angrboda I have a roommate that's played "quite the quantity" of Dark Souls and it'd pretty popular around my social circle, so I sort of absorbed it by osmosis, but I can see how if I hadn't known that, I'd have missed what it does and how it works.