It might be fun to add core only abilities to the game. Essentially abilities that would go away if you chose an elite spec. The goal is to be fun and thematic rather than adding power. Here's my list:
Engineer: When engineers use an environmental weapon it explodes. Also when engineers defeat an enemy there is a 15% chance it will create a relevant environmental weapon.
Elementalist: When they take elemental damage they are attuned to it slightly reduces the cool down on weapon skills. Not by a lot but just enough for you to consider maybe standing in the fire and calling it alacrity
Guardian: All heals to the Guardian over 100% will spill over to the most damaged ally within 900 units
Mesmer: Out of combat, mesmers can use illusions to interact with the world allowing them to do stuff at range; gathering resources, resurecting allies, and looting for example. The illusions would vanish if attacked or if the mesmer enters combat.
Necromancer: Necros res other players at twice the speed as everyone else but loose half a percent of health per second while doing it. Also resurrecting a necro grants the resurrector quickness.
Ranger: After killing an enemy a ranger can track that type of enemy on the mini map for a few minutes. Tracking a type of enemy gives a small, like 1 percent, damage reduction agaist that kind of foe.
Revenant: Revenants can see hostel npcs a few seconds before they spawn
Thief: Thieves can see enemy traps they are close to (like in melee range). They can also reset any trap they are near when it trips; including their own. Reset traps are lesser versions of the original and can't be reset.
Warriors: Warriors respond to shouts they hear by repeating it duplicating the effect to a lesser degree.
What do you guys think?