Thanks Ciaran, I was going to suggest Carex incomitata but every other CNM sighting seemed to be at higher altitudes (1000m+), where this was at 500m, so that was enough to put me off the suggestion even though it looked right.
I agree with your ID. I see C.appressa on a near daily basis so I’m quite familiar with it, this was definitely different. It was really sharp, if you grabbed it and tried to pull it out you’d be cut to pieces.