General rumor mill just mostly talks about how Bruce was totally doing magic when they were at the Approach (in the Fade, really, but details are probably muddy now so it doesn't matter). He was shooting fireballs and the like from a staff. He's been dragged to do some magic around Skyhold and has been formally drafted to serve the Inquisition as a proper mage since then, so at this point its more or less an open secret. \o/