Aren't you immune to maladicts while lifeshielded? So the point of lifeshield is to make it so your arial swordspec buddy can tank forever vs that dagger spec. You'll use less mana lifeshielding than healing once your buddy drops his weapons and acan't dodge anymore. Or if the guy has trapping. If you lifeshield him he can just wear +damage gear and just pincer spam with no fear of dropping the heavy weapons. Unless it's not true that maladicts are prevented, but I think they are.

Even if I'm wrong about that, lifeshield does very fast healing. If your goal is to make someone not die, lifeshield can "heal" 1000 hitpoints faster than anything else. So your bard buddy rushes in to fiend three giant sword specs. He wouldn't survive the first two rounds if you try to just heal through damage, but with lifeshield, maybe you go oom but maybe your bard friend survives it.

Lifeshield isn't something to use all the time but it's very powerful at the right time.