The Animagus thing makes sense, but Im not sure about the rest of it. By the time you reach the 5th Year, their doesn't really seem to be that much progression in skill. N.E.W.T. level might be representative of gaining a level. My point here is, if you look at it, Dumbledore isn't a 20th level wizard. I think this whole setting/variant could work very well as an E6 or E8 variant.
Don't know how helpful I could be, but if theirs a way I can contribute, I will.
It's described as slashing, so it should be slashing damage. Everything else looks fine to me.
Also, is the ranged Touch Attack in combination with the DC 25 save? If so, thats a pretty big obstacle to cast a spell.