After all in Numenera it's not unusual for a Dagger or Broadsword, or Greatsword to be shaped as a giant bladed circle or to be equipped with a T-handle or shaped an any number of exotic ways, it doesn't make it a different weapon for game-rule purposes.
Knife or Dagger:This is the baseline level of utility. A knife or Dagger can be used in Melee or thrown a short range. Other light weapons will sacrifice one or the other for different effects.
Punching Dagger:Punching daggers cannot be effectively thrown, however they are useful for those trained to fight unarmed. Any character with the Needs No Weapons ability or Needs No Weapons focus can use a Punching Dagger to give their unarmed attacks a Weapon Distinction (Numenera p.115). A typical Punching Dagger would provide the Stabbing distinction, while a "Bladed Hand" would make the attack "Slashing", and good-old-fashioned "Brass Knuckles" would be Crushing. The defensive bonus from a 'Reaching" weapon of this type would work well to represent Tonfa.
Sisk or Razor RingThese throwing weapons lack a proper grip to hold in melee combat, however thrown correctly they have a "boomerang" effect if they miss the target by a narrow margin. A Razor ring or Sisk will return to the thrower and be caught if the roll missed by the target's level or less. If the weapon hits it does not return to the thrower.
Example: Thrown at a Level 2 guard, the weapon needs a roll of 6 or better to hit, on a 4 or 5 the weapon returns to the thrower, on a 1 -3 the weapon misses completely and has to be retrieved.
Thrown at a Level 3 Captain the weapon hits on a 9 or better, returns to the thrower on a 6 to 8, and misses completely on a 1-5.
Note: Yes with increased target difficulty means a greater chance of a "Boomerang Effect", however this simply reflects that with increased target difficulty is an increased possibility of ways to miss.
Suggested Weapon Intrusion: The thrower reaches out to catch the returning weapon, but the weapon strikes their hand. Thrower takes the weapon's damage (including any spent for effort) and cannot wield a weapon in that hand until they have been healed. Fighting from the "Off Hand" imparts a 1-step penalty to attacks.
The rapier is double the cost of the Dagger, however lacks the ability to be thrown. Rapiers are used with a fighting style that emphasizes defense and should be considered "Reaching" by default, in addition to whatever other distinctions they may have if any. (typically Slashing or Stabbing).
Like the Rapier this is also a "Reaching" weapon. It may also be "Entangling". An "Entangling" weapon may be used to inflict damage, or it may be used to "Stun" (Lose a turn) a creature with a level of the weapon's damage or less (attack roll required every round to maintain effect, miss means the target gets free and may act normally). Higher level creatures may be entangled by using effort to increase 'damage', however to maintain the effect Effort must be spent every turn.