Chaykon said: If you had only your mouth since birth, you too would probably learn to use it for something other than eating.
Pretty much this. I've read and watched stories of people who dont even have 2 arms let alone hands and they can do just about everything with their feet.
Bapabooiee said: I think the question is, more so, how did she write it that legibly?
Well, some artists will portray a Yukkuri Reimu as being able to use her braids for either wings or hands. post #338422 for example has Yu-Reimu using her braids to type a computer. Sure, typing is different from holding a writing utensil, but you get the ideas.
Alternatively, she took it easy like Catloaf said.
Take it easy! In this case, Reimu used -wa, instead of -ne, which is a very Ojou-sama like phrase