I've had these up (flanking our front door) for probably 3 years now.  I loved the look of these when I first bought them and still do but they are completely rusted already.  I would think an outdoor light would be a bit more durable.  We live in New England, so yes the weather is harsh, but an outdoor light should be able to be out in the elements.  I have the "weathered bronze" finish - maybe the other finish holds up better.