well if you can survive long enough(and be strong enough to kill them) for dragons to start showing up, they can potentially give a shield. Though even if they did it'd most likely end up being junk, like wooden or medium iron. Or if you survived till exp lvl 25 then chaos knights can provide some nice gear, shields included, and even better they actually aren't all that tough. But surviving that long is another story.
I haven't yet finished an ADOM game, but i haven't given up on trying yet either.