<This guy right here, just watched all of Heaven's Lost Property.. I can say I'm hyped for this now. I also think that the combination of Aegis and Pandora as suggested works better than an over time thing, over time is cheap bro.
If she needs to have the button held down to use the shield, which has a one second start up, and only heals every five seconds, that leaves a little chance to heal at all because she'd probably be vulnerable while trying to activate the shield. I personally don't find this cheap. o.o
*clicks like button*