The arete forms the eastern rim of Cwm Glas Mawr. Climbed as a winter route sometime in Jan 1987 I think, and again as a summer route in July 1998 when overcrouding and queueing for routes put us of climbing on Cyrn Las.
Certainly one of the least known of the snowdon routes. I have only done this once and admittedly not by choice it was used during some summer ML training