No one wearing the red cross can be armed... medics these days do carry riffles but the don't wear the red cross, if so they can't be armed. That would be against the geneva convention.
I think that some, if not most American medics serving in the Pacific theatre carried a 1911, since the Japanese went after medics specifically. Not sure if Canadian or British medics would have done the same. If they did, it would have been a Webley revolver or Browning Hipower.