Weapons
Without weapons, combat damage defaults to Complications - PCs are bruised, winded, sore, and shaken up, but usually nothing that won't fade after the fight. Characters can still choose to inflict Injury deliberately, but this requires a Wager to represent the extra effort and intent needed to cause lasting harm with bare hands, or at least a believable explanation of how their action could have caused real Injury, such as a believable improvised weapon - often the ground or a wall will do.
Weapons make conflicts dangerous by changing this default. Armed combat uses the normal post-fight recovery system - some Harm might be Complications that fade quickly, but some could be Injury that takes time and care to heal, though groups can say some weapons like light truncheons and wooden training swords are still just Complications by default.
Maneuvers in weapon training add to attack rolls and can apply to active defense or Wager effects like called shots, making them more effective and useful in general. Yes, you can use Wagers to "pull your punches" by declaring explicit Complications at the cost of some skill.
Significantly longer reach weapons allow a free action each turn to maintain a Longer Reach boost if you choose to use it. Foes can oppose this with their own free action. If the opponent wins, they gain an Inside Reach boost and negate the reach advantage so they can attack that turn. If the reach weapon wins, opponents with lesser reach are held out of range and cannot make melee attacks. Note that most sword-sized weapons count for a reach advantage against an unarmed opponent, or one with just a small weapon like a short knife, just as most polearms count against shorter weapons like swords and maces.