What Gear Does
Creates Narrative Permission - This is gear's primary function. Even without mechanical bonuses, gear alters what actions are possible. Your archer needs arrows to shoot her bow. No picks for a lock means improvised tools and situational penalties. No weapon means unarmed combat defaults to Complications unless you're deliberately doing something to break bones.
Provides Mechanical Benefits - Gear can amplify existing skills, but avoid the trap of flat numeric bonuses. A knife doesn't make someone a better fighter - training makes better fighters. Focus on gear as a vehicle for skill, where ranks in weapon or armor type Maneuvers add to relevant rolls. A warrior trained with swords applies those Maneuver ranks when using one - and not just fighting, but any time it reasonably applies. A heavy weapon will slow a PC in a chase, but familiarity helps!
Weapons also have sharp points and edges, add leverage, and can change the type of harm done. Some gear might have unique Traits that can bend the rules, but that will usually be special items, not just mundane gear. An unbreakable sword, silent boots, or a ring of invisibility change the narrative, which is always more powerful than just adding numbers.
Creates More Narrative! - Gear often comes with built-in drawbacks or "Snags" that generate story complications. Like Plot Hooks, these limitations can sometimes work in your favor - but they don't provide Karma.
Walking into town armed and armored marks you as potential trouble until locals know better - one doesn't stroll into the marketplace with a strung bow to buy sausages. Using weapons to intimidate might work once, but creates lasting reputation that affects prices, available services, and attracts attention from both the watch and local toughs.
Gear can also apply Hindrances, usually to specific activities - most any sort of heavy weapon or armor is going to be a serious Hindrance to any attempt to swim, but "dealing with it in the narrative" is simple - drop it, or take it off. If you're already in the water, dropping your expensive broadsword might make it really hard to recover, and taking off armor could take long enough to kill you…
Don't swim in chainmail or attempt delicate calligraphy in plate gauntlets. Heavy gear slows movement and creates noise. Obvious magical items draw unwanted attention from authorities, thieves, and people with problems they hope you can solve.