That is way to broken. 10% mitigation and aoe heals for 25% of your damage to most or all party members is waaaay to strong. Its balanced perfectly fine as is vs other tanks single target assist buttons thay all last 6-7 sec.
The only issue with glint is that its hard to use on a controller effectively without a macro. The effect of the skill is A-ok. Just make it a little more user friendly like select the nearest target if you dont manually select one (for example) or something else to make the targeting less precarious on controller.