You could go for Avalanche (much better than Ice Beam because it's physical) but then you have more chance of getting hit - well you want to get hit so Avalanche has power 130!!
Endeavor is a great choice for when your HP is getting low. Or, Swampert can also learn Outrage by move tutor.
You do have three great attacking moves already, so you could go for a stat move like Toxic or Stealth Rock.