If you could earn another class's utility?
Shadow refuge on my engie. Though I think if anyone could learn any other class’s utilities we would be seeing (Or not) about 500% more people just running around invisible, especially in wvw
Every class except for Mesmer: Portal.
Mesmer: Shadowstep.
That said, I vehemently oppose this suggestion; it’s the reason Guild Wars 1 was never able to be balanced, by opening up secondary professions, there were too many combinations, many of which became overpowered and overused.
I’d rather see a quest to earn access to another race’s skills. Spend time working with asura to learn their skills. Serve with some charr forces and you pick up some of their weapons. Learn from the spirits of the wild, and maybe they’ll allow you to call on some of their power. And so on…
delicate, brick-like subtlety.