He wouldn’t have had enough information to conclude that Harry had invented a new type of Transfiguration—he would probably think it was a particularly powerful cutting hex for a first year, or something. Still stupid of him not to have made inquiries after two times witnessing its effects (cutting through the wall of Azkaban, felling the trees).
Especially knowing that Harry almost offered to explain it to him (after Azkaban).
Quirrel’s answer :
it is too rare that I find a person whom I cannot see through immediately, be they friend or foe. I shall unravel the puzzles about you for myself, in due time.
He wouldn’t have had enough information to conclude that Harry had invented a new type of Transfiguration—he would probably think it was a particularly powerful cutting hex for a first year, or something. Still stupid of him not to have made inquiries after two times witnessing its effects (cutting through the wall of Azkaban, felling the trees).
Especially knowing that Harry almost offered to explain it to him (after Azkaban). Quirrel’s answer :