Kind of. It's at least pretty in depth with regards to altering what your character can do.
http://www.gameinformer.com/b/features/archive/2013/12/27/the-character-progression-of-destiny.aspx
Green: Everything gets the XP [reward] unless you have an XP bonus or something. You might have a piece of armor that gives plus XP to your weapon. So you might take that 10 XP on every piece of gear except your weapon, which might get 11 XP because of the modifiers. You might have a consumable or a perk active that gives you a bonus to how fast something else levels. It can vary from object to object. But generally speaking were definitely not asking anyone to make any hard decisions like, Maybe I should only equip this one piece of gear because thats the only thing that needs to level up so it power levels that one thing. Were trying to keep those mechanics very straightforward.
Green: The three things that all characters can upgrade are their weapons, their armor, and their focus. Those all level up as you use them. So when youre wearing your armor and earning experience your armors leveling up. When youre using weapons to get kills, those specific weapons are leveling up. And your focus also levels up when youre getting kills or completing activities.
Green: A focus is a thing that captures all of your abilities in one bundle sort of a thematic bundle, but also a functional bundle. It carries your grenade abilities, your super attacks, it carries certain passive abilities that change the way your character plays. The focus is the thing that defines how your character is going to play at both the lowest and the highest level. Its what your character is thematically about and its also functionally what abilities you have available to use.
You could call it a spec. You could call it a build. You could call it a lot of things. For a long time we called them builds, but your build is a bigger thing because it also brings into account which weapons youre using and what modifiers are on your armor. I want people to be able to talk about playing a Void Warlock sniper build, which is something that encompasses more than just the focus item.
Weapon tuning arguably sounds the most involved.