The shears themselves raise a question about the true source of Emma’s magic. Is she magical because she is the Savior or is it from her being a product of true love? Throughout the series the two things are linked so often it is not clear which elements are the cause of the different parts of Emma’s various powers. I can see it being that the shears are used on Emma against her will (either through a villain striking against her or circumstances being such that she has no other choice) and she maintains her magic, even if it is weaken through the loss of the savior bond.
“The truth isn't easily pinned to a page. In the bathtub of history the truth is harder to hold than the soap and much more difficult to find.” - Terry Pratchett