It's something someone else says about you, not really a title granted by the game. And the context of course would be limited to the persons personal experience, which isn't necessarily objective by any means. As far as healers go I've seen some pretty good ones. Single heal/single tank t9's before echo was really huge. Single heal/single tank Shiva ex not too far after release. Folks with pre lvl 60 savage coil clears. Granted ast hasn't really had these chances yet because they are a new class and content is limited at this point but just keep practicing and pushing yourself to be the best you can be. That's all that matters in the end. Not what some other people think of you.