Cork is peeled off the trunk. An unsharpened edge would help to pry the bark away without actually cutting into it. I've been to a cork 'farm'(?) In Portugal a LONG time ago. If I had paid more attention to the too l s, I could be of more help. As it is, my thoughts are speculative.
Check out the blade used at the 3:20 Mark in this .
https://m.youtube.com/watch?v=JewMikbKOI0.
Similar, but with what seems to be a keen edge. Watching the earlier footage, I see axes being used on the trees, but the ax handle being used to pry the bark from the trunk. So, again a less than sharp edge could be the intent.
video