Superior Rune of Altruism - fury time
Superior Runes of Altruisme gives 3 stacks of Might for 10sec and Fury for 5sec when you heal. With a 25% boon duration bonus, you get 12,5sec uptime for Might and 6,25sec uptime for Fury.
So what you describe sounds right to me.
Ok, ty for the info. It would be nice to add the base times or something to the tooltips.