I was just watching Harry Potter "Prisoner of Azkaban". Just before the scene where Harry casts the patronus spell to get rid of the Dementors, Hermione says:
Only a really powerful wizard could have conjured it.
I know the scene is a little bit different from the book where Hermione isn't with Harry at that point, but either way the question is the same.
At that point was Harry a really powerful wizard?
What does "really powerful wizard" mean?
Could the part of Voldemort inside of Harry have enhanced Harry's powers to help him cast the patronus charm even though Voldemort himself doesn't cast that particular spell?