When it comes to healing, all the Alicorns are capable of self-healing just about every injury. I don't know about Dawn, but I'm personally against healing spells. It would require insane amounts of energy to force cells to multiply and so on. The most I would agree to are spells that speed up recovery; giving the body extra energy to do its own healin, so to speak.

And here I'm talking about making a 2 months recovery into a 1 months recovery. Nothing more than that, in my opinion.