One of the fun things to look for when you crack open a new RPG is to see how skills are handled. Now, I'm not talking about mechanics of dice pools versus static ranks and bonuses, but rather what a skill is capable of doing for you. See, in some systems - like GURPS for an extreme example - the skills are very specific in what they do. Like, to the point that in GURPS you have 3 skills for any particular fighting style: show, sport, and actual combat. In other systems (nWoD is my favorite example for this) the skills are very broad and cover a wide range of ability. Both systems have benefits and weaknesses. Today, I want to talk about that.
The broad application seems to be the more popular way for newer systems to do things. It is easy to see why, especially if you've ever tried to write out an RPG yourself. Writing skills is tedious and monotonous, and very quickly gets boring. I mean, you describe in one to two paragraphs what the "Guns: Pistols" skill lets the player do, then do it again for "Guns: Rifles," "Guns: Submachine Guns," and "Guns: Revolvers" skills before realizing you get to do it all over again for "Guns: Heavy Weapons," and "Guns: Mounted." More to the point, when you give a skill a broad application you free up points for the character to diversify.
For example, take your typical thief character. They need a way to pick pockets, locks, bypass security, circumvent other hazards, and otherwise get the goods they came for out. However, they also need knowledge of what the items are, their worth, means of selling them, and likely lore about the items. Not to mention normal skills like detecting people, combat ability, lying, and other social skills. Being a thief takes a lot of skill points. But what if all of that could be summed up with "Burglary," "Lore: Art," and "Social?" Suddenly, our thief has his job covered, but is also able to diversify and take on secondary talents like driving, or being a member of the gun club. Pretty awesome, right? It is pretty cool, especially as a player, and it is the strength of broad application. However...
On the other hand this can also get you in trouble for some things. For one, in the example above, I have all of the social skills under one category. Yeah, it kind of makes sense, but that also makes it a very powerful skill. Sadly, I don't know of a system that does this. However, I can pull another problem example out of the New World of Darkness. In nWoD you have a skill called Crafts. If you want your character to be an artist you have a high crafts skill. After all, it governs drawing, sculpting, and a number of other artistic endeavors. However, if you want your character to be a mechanic you also have a high crafts. Suddenly, my character with 5 dots in Crafts from being a high level/famous sculptor is also an amazing mechanic too. Now, house rules exist to get by this, but that doesn't make it not a potential problem in a game. Another example would be the burglary skill I listed above. What if you wanted to play a pick pocket? You take the burglary skill. However, now your character is capable at doing a lot of other things that aren't reasonable considering your background and you just don't use. Your character, who has made a living picking pockets and roaming the streets, is suddenly able to - just on a whim - pick the lock or bypass a vault door because they can lift a wallet like nobody's business. This almost unrealistic level of skill application for some characters can cause problems for some GMs, especially when it comes to challenging their group. It is also one of the weak points of broad application. Things can be almost too broad to be comfortable and it leaves people wondering what they should do.
Mysteriously, the problems with narrow application - and strengths - are basically the inverse. With a narrow application you are able to specify where your character is strong, weak, and what exactly they're capable of doing. You can have a world class sculptor who isn't also a world class mechanic. You can be a top notch pick pocket and have no clue how to get past a locked door. You get to specify these details of your character and in turn give a fairly strong mechanical representation of who that character really is. It is harder for someone to take a character with narrow application skills and play them vastly different (role wise at least) than the character was intended to be played.
At the same time these specifics can be costly. Characters that need a lot of skills are now a lot less able to diversify. This could be ok with you, after all they chose to need a lot of skills, but it can cause problems when every time the character is out of their element they become near useless. It also leaves itself open to glaring but simple mistakes. How many times have you forgotten to write down "detect traps" for your thief because you'd just wrote down all of the other skills your thief needed and it simply slipped your mind? I did the same thing one time with Search. Other times I've been so paranoid about not missing a skill that I had "Open Locks" on my character sheet three times. Simple mistakes, yes, but a lot more possible with narrow application skills.
The Middle Ground
One system I know of - Unknown Armies - takes an interesting approach to covering the difference between broadly defined skills and narrowly defined ones. Namely, it lets you name your own skill and in doing so define what it does. So, if I have down "Baseball Bat!" as a skill, it may serve a similar purpose as your "Weapon Master" but when neither of us has a bat in our hand, and instead has , say, a knife, your skill stays relevant while mine really doesn't. It is an interesting system to be sure, but only really being mentioned as an alternate from the norm.
Do you have a preference between these types of skills? Would you rather have power that you just don't use because it doesn't "fit" your character or only be able to do the things you want your character able to do? How does your favorite system cover this? How would a system you made cover it? Sound off in the comments.