I gave two staffs to Lydia which she loves to use. So now she is dual wielding death staffs with what seems like infinite charges. Is this correct behavior?

In Fallout only the default companion weapon had infinite ammo, so this might make companions too tough. I know she has infinite arrows (and actually refuses to use better arrows as far as I have seen.

I had a encounter with some bandits. Shot a sneak arrow and it took of about 10% of it's health. Then Lydia just goes "HAHA!" and fries the bandit in one second flat. And the five other that follow, all while reload my bow...

Also seems to be some error with companions and staffs. Sometimes Lydia starts to grill someone with flame, but NEVER stops, even after they are dead. She must hate the enemies of her Thane.