Crossword Genius

Blade worn must have edges switched (6)

Ross

I believe the answer is:

dagger

'blade' is the definition.
(I've seen this in another clue)

I cannot understand how the remainder of the clue works.

(Other definitions for dagger that I've seen before include "Macbeth's weapon" , "''Is this a ... which I see before me'' (Macbeth)" , "Stabbing weapon" , "Short knife for stabbing" , "that has an incisive point" .)

I've seen this clue in The Times.
Want a hint initially instead of a full solution? Install my app