I can okay Wrathion learning to make a wand that is just around 50% compatible with Hermione: she will not be able to finalise some spells, and the ones she can complete will be very weak in effect, compared with their intended impact. Some high-cost spells (like the Unforgivables, the Patronus) won't work at all. Think of it as the wand equivalent of a phone with an extremely bad connection.