The light applies to one of the weapons.
Unfortunately, since Patch 9, it's not necessarily the weapon currently displayed on the character (which, is an issue indeed).
I had to click on the weapon instead of the character (and that's a bit tricky).
Yup, know that, and I looked to see that the light was applied to his quarterstaff, which
was the currently equipped weapon. Yet the staff wasn't lit up, and there was no aura of light surrounding the character. It's definitely a glitch of some kind.