Not, I don't think, a ewer.............those tend to have wider mouths, and substantial lips, and don't have a stopper.
As a generalization pieces with handles are jugs, and those without are decanters............but as with everything there are exceptions. You can have whiskey decanters that have handles, and claret jugs with either stoppers or metal lids - in fact the extent of variation is surprising.
As you have a lip, then I'd suggest either a claret jug, carafe or water jug.
It's possible you are missing a stopper - are there any circular wear marks within the neck - is there a scratched 'matching No.' somewhere in the area of the lip/neck - if this did have a stopper originally, then the same No. would have appeared on that.
I'm unable to see the pontil mark to which you refer - usually, the scar would have been removed when cutting the star - however perhaps I've missed seeing the mark.
In my opinion, the cutting on this looks to be............. hollow diamonds on the neck and oval printies/punties on the main body, with patches of cross hatching around the waist.
One of the down sides of collecting glass - especially traditional shapes that have a long history - is that patterns/designs have been copied ad infinitum, so then you have to look at other issues to assess age.
Most decanters with some age have staining or tide marks - base wear should be pronounced if this were C19, and all those arrises between the ovals would have less than perfect sharpness as they are the first point of contact with other objects. The cutting here doesn't look especially age related i.e. it doesn't show any specific period to me, and I'd suggest first half C20, but that is only my opinion.
I believe that the term lens cut refers only to circular cuts, but I could be wrong on that point.
But for a quid you can't really go wrong, and if you work the boot sales regularly you should find a stopper that will have a reasonably acceptable fit, even if not the right match of cut.
P.S. Chris - what in particular makes you think Victorian c. 1890?