I know is is a thread about magic as a general and not only the Espers and their powers (which I think is happening that they are able to do the trick only with their minds and don't need any extra technology for their "magic"). However there is still one aspect that was not mentioned yet - the healing skills.
My knowledge of the lore is genreal at best but I gave it a thought and eventually found out it all pretty much works together and managed to give myself a reasonable explanation.
If you want to follow my train of thoughts, here it is:
So how it works? As stated before already, the magic in Wildstar is based on manipulating the Primal Elements and Life is one of them. One of the possible ways how to work with Life power is to play with the cycles happening in the body. So in this case, I have no problem imagining pumping primal life into injured person, so their metabolism boosts up its regenerative powers to such level, it can heal the wounds in no time.
Now it only brings another question - where to take this primal life energy from? There are four possible sources.
1) The Esper themself - same like they use their own mind powers to make their illusion real, they can use their own life power to carry onto someone else. The only issue here is, that their healing powers might be pretty limited, because the more they heal, the weaker they become. (At this point I ask myself, how much the Focus regenerates during battle, because I have no experience with it yet)
2) The healed person - in this case it would not mean to "pump" more life energy into the wounded one but more like preventing the life to "leak" from the broken body and focus on mending the wounds. The weak point of this image is, that it kinda crosses the idea of healing in combat - when you manipulate someone's inner power to heal the body, I bet it kinda weakens the other body functions, so the healed person won't be much of a use in the fight for a while. Also, since the primal life is also somewhat responsible for the aging process, this can pretty much mean, that every time you're healed this way, your overall lifespan shortens by some portion. But hey, it saved your life now, so I guess it still counts.
3) The surroundings - since the primal life is present in every life form, it can't be that hard to simply take tiny bit from everything around, the grass, trees, bugs and other animals. Taking a tiny bit from every individual would eventually yield enough to mend the healed wound. This time I imagine the healers' Focus to represent their ability to concentrate on all the small sources of life all around them.
The interesting part of this idea is, how would such thing work in places with little to no sources of life around (like outer space or other extremely hostile environments). I think in such scenario they would have to deal with it like in the 1) and 2) option. After all, the healer and the healed one are still carrying their primal life within them.
4) The enemy - more situational, because it's not always a combat, when you need a heal. It can be just a casual injury or something. But still, in most cases the enemy would be a living being too, so a good source like any other, when we think about the 3) option. But this is actually in the game already with the whole Lifesteal mechanics. And Espers do have some abilities with lifesteal implemented. Or just such, that do both harm and heal at the same time.
Now I must say, that the 4) brought me to another train of thoughts: Vampire Espers. Just think about it, if they are able to steal some else's life power to heal themselves, how hard it can be for them to suck out all of it and leaving only dead body behind? Or to do any other dirty tricks when manipulating the primal life. It is responsible for the aging process, right? So why not to age that strong warrior into harmless and weak old man? How hard such things have to be, that when it comes to combat, Espers rather conjure flying blades to cut off their enemy heads?
What do you think?