[Daphne] was not taught anything that could possibly be of any practical use whatsoever. (3.65)
Daphne often frets that her skill set doesn't mesh well with island living. Practicality all depends on context. Starting a fire from sticks and flint would seriously not be practical in British polite society. In fact, it might get you into some pretty hot water—and not the kind used to make tea.
Who'd want a pony when you could have the whole universe? (4.10)
Daphne eschews the typical gender norms, wanting a telescope instead of a pony. Would Marie Curie have discovered whatever she discovered if she had played with My Little Pony—or do the toys you play with as a kid even matter?
The secret [to invisibility] was to wear ribbons in your hair and skip everywhere. (4.25)
If Harry Potter knew this, he wouldn't have needed that invisibility cloak. (And we'd love to see Daniel Radcliffe in pigtails.) But seriously, what Daphne means here is that everyone overlooks girls. Turns out, they probably shouldn't.