For that effect, there’s two possibilities judging from that video.
First and less likely possibility, they had some special kind of engine/material/rendering trickery to duplicate the character mesh and push its faces/vertices out using some kind of offset, with the masked out “glow” texture applied.
Or the second and more likely possibility, is they created a second version of the character mesh in their 3D software that was modeled to rest about an inch or so (scale wise) over the character’s main mesh and rigged to the same bones, and apply the same above mentioned masked out animated glow texture. I think most games use this method, since it’s cheaper than processing anything in real time, and the “glow mesh” doesn’t need to be as highly detailed as the character mesh underneath it.