The Fight skill covers all forms of close-quarters combat (in other words, within the same zone), both unarmed and using weapons. For the ranged weapons counterpart, see Shoot.
OOvercome: Since you don’t really use Fight outside of a conflict, it’s not often used to overcome obstacles. You might use it to display your fighting prowess in a demonstration, or to participate in some kind of regulated bout or sport fighting, which would allow you to use this skill in a contest.
CCreate an Advantage: You’ll probably use Fight for most of the advantages you create in a physical conflict. Any number of special moves can be covered with advantages: a targeted strike to stun, a “dirty move,” disarming, and so on. You could even use Fight to assess another fighter’s style, spotting weaknesses in his or her form that you can exploit.
AAttack: This is self-explanatory. You make physical attacks with Fight. Remember, this is for close-in work, so you have to be in the same zone as your opponent
DDefend: You use Fight to defend against any other attack or create an advantage attempt made with Fight, as well as pretty much any action where violently interposing yourself could prevent it from happening. You can’t use this skill to defend against Shoot attacks, unless the setting is fantastical enough that you can catch missiles or swat them from the air or use laser swords to deflect blasters.
It’s a given that most games that you play with Fate will feature a decent amount of action and physical conflict. This is another area of emphasis, like with the Crafts skill, where the skills you choose to have for combat speak volumes on what your game’s about.
In the examples, we’ve got Fight and Shoot as separate skills, to give us a basic division without getting too much into minutiae. Notably, though, this suggests that fighting with a weapon and fighting bare-handed are pretty much the same—there’s no inherent advantage in doing one over the other. It’s a pretty common choice to further separate unarmed and armed melee—into Fists and Weapons, for example.
You could specialize even further if you wanted different classes of weapons to have their own skills (Swords, Polearms, Axes, Plasma Guns, Slugthrowers, etc.), but again, we recommend you not go too crazy with this unless it’s really important to your setting. Specialized weapon use can also be modeled by using extras.