Aaah, but a bevel is a big one (and I agree with your Dad), an arris is a tiny one, specifically at 45 degrees to a "main" polished plane.
I like arris, because it sounds like somebody saying Harris with a local accent, and of course, Harris is an incredibly important name in glass. :sm:
I can really see why you're wondering about that vase being potentially Dartington, but can I shove WMF in as another possibility? But wait until somebody who is far better at WMF than I am to come along!