Using the "resurrect" console command seems to have the nasty side effect of "resetting" the Companion. IE: anything that they had on their person will be GONE.
Oh yeah, I forgot about that. Handy for replacing missing items they're
supposed to have, not so handy for stuff you don't want them to lose.
Your companions can actually be finished off while crouching, even by enemies. Enemies will turn their attention off her when she crouches but if you're still fighting around her one of them might accidentally hit her or she might get aoe to death.
It's funny how persistent these rumours become once they start! A bit like "placeatme" being a good idea which still persists years after people were repeatedly warned not to use it (and to be clear, do
not use that command for summoning NPCs!) Anyway, if there's any doubt, most if not all companions are completely vulnerable however lucky people have been so far.
Oh yeah, one thing I forgot is that there's a bug that stops companions' stats being recalculated on level-up: disable/enable is reported to calculate them (use with caution: although it seems to be trouble-free, you can never tell, so make a permanent save first) and dismissing and rehiring them is reported to also work, though I suspect they may need to make a transition to another cell first.