DC switch for wall sconce

Most AC switches aren't rated for DC usage, and DC switching is indeed rather more demanding than AC switching (as the current waveform doesn't periodically pass through zero, which helps kill any slight arcing as the switch contacts are opening).

That said, for an application such as this, there's absolutely no harm in trying a decent quality AC switch. Most likely it will work fine, at least for a good while. If it fails, you can replace it again. I would not recommend an AC switch for a safety-critical application. (The failure mode here would typically be the switch is stuck on or possibly off. There shouldn't be any problem with it overheating provided it's rated for the expected current.)

You may be able to find a more or less exact replacement switch from Digi-Key or Mouser or other similar companies.

I replaced the push button switch in one with a rotating switch I got at the local hardware store

I replaced our bed room wall lamps with lamps I bought from CW.
You should be able to replace the switches. Take one out. Check your local home supply store or electrical supply store.

Amazon has a bunch if you poke around.
Here is the first one I found ( different shades available).
But, if the switches or wiring is faulty, new lamps won't help.

....LINK