Note that this is all very IMHO and based on my unrealized Savage Guild Wars conversion.
1. E6. All heroic characters of GW universe are not beyond a reach of a average folks. The magic and skills make them powerful, but they can be hit and eventually brought down always. They also lack access to world changing magic. The real game changers (Asura gates, artifacts, golems, magic swords) are items which take a lot of knowledge, cooperation and work to craft - in fact most of these items are beyond ability to create.
2. Skills. Characters who devote themselves can learn special abilities which allow them to go a little beyond limitations of standard E6 creatures. These abilities can be learnt at any time, provided certain resources (and effort, and time) are used.
2.1 (this is highly GW1) Each character may attune themselves to an archetype. This is a prerequisite to learning skills associated with the archetype. Highly experienced characters may attune themselve to secondary archetype, too, although effects of skills associated with secondary attribute are significantly weakened.
2.2 (this is highly GW1) At any time you may use only up to 8 (or 10) specific skills. This limit is a function of your inner strength.
2.3 One only needs to be rested and meditate for an hour to change currently active skills.
2.4 Unless otherwise stated, skills require a standard action, and usually are a stronger, more efficient version of such action.
2.5 Bringing someone from the dead is something any healer can do easily as long as: one hasn't been dead longer than minutes. One's body is not damaged beyond healer's ability to physically repair it.
3. Known archetypes: (see all classes from GW1 and GW2)
And that's it.
Pity I never found the time to flesh it more.