Balustrade
Basically, it’s a railing of some kind, like those on a balcony or open staircase.
Technically, the balustrade is the horizontal part (where your hands would rest), while the vertical parts are called balusters (the balustrade sits atop of the balusters).
It comes from an Italian word for the pomegranate tree, which some balusters evidently resembled.
Why I Looked It Up
Warren had planned to place a Latin inscription on a balustrade…
Postscript
Added on
I found another reference in Neuromancer:
The girl’s face appeared as abruptly as one of Riveria’s projections, her small hands on the polished wood of the balustrade…