A glass wall light usually does two things at once, lighting the wall through the glass and lighting the glass itself. That means the colour of the wall counts. Coloured glass reads best against pale plaster, while clear glass needs a darker ground for its detail to show.
Look at the projection as well as the width. A glass piece standing well off the wall needs a corridor of 1.2m or more, or it will be knocked. In a narrow space, choose a flatter fitting and fix it above shoulder height.
