So I spec my guardian to precision damage and toughness. I noticed that some of my team mates are not getting might during the usage of Empowering Might on my guardian honor spec maybe it's because of the stacking rule where you can only get 5 allied targets. Also another question is "what is the cooldown on it's effect?" because I don't think it would make any sense when a guardian just aoes a mob with 50% critical chance and the team would get a 25 might stack for 5 seconds
The "cooldown" for Empowering Might is only 1 second. This really only ensures you don't do exactly what you mentioned, and rack up a bunch of Might with a single ability.
Every time you get a critical hit you and allies within range gain Might for 5 seconds. That range is 240 units.
According to the official GW2 wiki: "Distance is defined in terms of units, which are essentially equivalent to inches"