Well, I don't know how shields work in this setting, but one possibility is that shields do not let anything magical through, which would stop transfigured materials. Shields do stop bullets, so... is it a matter of speed? Do shields stop fast things like bullets, but let slow things such as knives through?
If carbon nanotubes work, then wizards who are not familer with the latest muggle science could still stab each other with very thin (to the point of near invisibility) diamond blades.
That sounds entirely too much like Dune to me. That's enough reason for me to doubt shields work that way.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 114, and also, as a special case due to the exceptionally close posting times, chapter 115.
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)