Looks like this has been patched now.
I don't think it's a bug or glitch actually - it seems to be a passive graphical effect tied to a Mage ability/passive. My Solas gets the same shimmery blue glow, kind of looks like little arcs of electricity at times. I always thought it was tied to Dispell/Transmute Magic buff, but he does have the Mind Blast upgrade as well. My Inquisitor is also a mage, but doesn't get this shimmery glow. She has no points in the Spirit tree either, so it could be caused by some ability in that tree?
I actually really like how it looks, but I don't know for sure what is causing it. You're right that it only appears after combat, and it disappears when you save/quit or travel to a new zone. When I first saw it happening I was thinking - wow, this is new, I accept this new thing - but now I'm curious...
I'd be inclined to agree that it's got something to do with a passive effect - perhaps how the Mind Blast buff interacts with Barrier? - but it smacks of a glitch to me. The fact that no icon appears in the status bar (like fire resistance, weakness, and others) and that it appears and disappears when you save/load makes me think persistent glitch rather than deliberate visual effect.
Perhaps it's a combat visual that hangs around by accident?
The idea that it's caused by the interaction with Mind Buff (upgraded) and Barrier seems right - it does trigger when you barrier yourself and then hit an enemy with Mind Blast. At least, I've been able to reproduce the effect multiple times by doing so. It's strange that it doesn't create any status icon with it, and you might be right that the visual isn't supposed to persist after combat. Would be interesting to know if it's working as intended? But there are so many other threads going on that I don't know if we'd get an answer.
Took some screenshots of it myself, for what it's worth:
http://i.imgur.com/hy5fROq.png
http://i.imgur.com/Ln4VVir.png
http://i.imgur.com/5mHcBa1.png
Good point, I don't know if it's actually functioning as intended. A lot of mage abilities appear to be bugged, from what I've seen around the forums - this might just be another (minor) issue. And yeah, the missing status icon is a bit suspicious.
Maybe when/if the mage abilities get patched, this will get resolved too? There's so many problems with the game right now, including Solas and Dorian's quest lines, that a little visual glitch like this probably isn't a priority.
