In reply to:

things that go over the lower legs tend to be talked about as a pair of things

It is not only true for items worn below the waist. A pair of scissors or glasses (i.e. spectacles) are also single objects.
I found it disconcerting to learn of eine Brille (glasses) and eine Schere (a pair of scissors) in German.
As it turns out, they're singular in many languages (bar French).