expect you're right Jay and my feeling is that this is from the C20 - and it could probably be used for either purpose.
I'm not aware that a 'castellated' style of rim is indicative of Waterford especially - at least it doesn't seem to be something recognized by Phelps Warren as suggesting that factory. This is noticeably different from a straightforward scalloped rim, which like the fan cut and saw tooth was a fairly common effect on much glass from that period.
Suspect you're also right about the thinness of the foot implying a more modern date.
The radial cutting under the foot is a feature borrowed from the period you suggest, and occurs on table glass from much of the C19 and some way into the C20.
Don't know where you sourced this one, but we have to remember that there are a many folk out there who spend a lot of time looking for older glass, and they usually know what to look for and where, leaving the likes of us with the copies.
Had this been 200 years old, and used as a vase or celery, then I'd be worried if I wasn't seeing considerably more wear, plus some damage to the high spots etc.
If you look at Phelps Warren, you will get an idea of styles, shapes and cutting of Irish and Anglo-Irish pieces from that period, and all you need to do then is find the stuff

Always useful to give the size/height if possible.