From what I've managed to get from Google, nerve death leads to paralysis, loss of sensation and reflexes, etc. The theory here is that nerve death should be unhealable, since death can't be healed. First question: does this sound logical to everyone, or am I reaching way too far? Is there something else you can think of that would be serious enough to leave someone permanently crippled despite the potential use of magic to heal injuries within approximately ten minutes?
Second question: I don't want my character paralysed. I do want her to lose at least partial control of one hand or arm. It must be something that could not be healed via magic. She will receive this injury in a fight, which can be roughly tailored to suit the injury, and it will be deliberately inflicted by another character who is trying to hurt her very badly (although not cripple her). Any suggestions as to what kind of injury this could be, and how she would be most likely to sustain it? Almost any weaponry can be used, if that helps at all.
As further information that might be helpful: unfortunately, she can be reached by healers within minutes of receiving the injury; it is very unlikely that the healers would mess up badly; she is in her early fifties and is a trained, battle-scarred warrior. Her opponent is a teenage girl, almost but not quite a fully-fledged warrior.
Thanks for any help, thoughts, or useful websites, 'cause my Google-fu is failing me.
Edit: You are all wonderful, thank you for the extremely helpful thoughts. Crushing looks like the way to go!