In Harry Potter and the Deathly Hallows – Part 1, we see Bellatrix throw a dagger after Dobby saved Harry and co., and in the aftermath we see Harry begging Hermione to give him anything that could save Dobby, but Hermione standing still.
Why is this? Is it too late for anything to be done? Is it because Dobby is not a human? We have definitely seen Hermione heal Ron before.