Yes hours legitimately 4-6 hours into trying to find the secret. I went to leviathan, whisper mission, crucible, private matches, gambit, raids, shattered throne (due to the multiple yellow bars etc. literal hours. From my conclusion it appears that when you are “locked on” (when the reticle of blade barrage is red) helps determine the energy recovered. That seemed to be the most consistent detail I could find. That activating that seemed to yield the best results. But for all I know there is nothing but an RNG code in the gauntlets. I actually just got URSA so I’m going to test that shortly down to each bullet.