List of weapons with reduced specials
It is a common misconception that weapons with a 9-star rarity or lower are reduced (i.e. their specials have lower activation rates and steal/drain less HP/TP/EXP from their targets), and that those with 10-star rarities or higher are unreduced with some exceptions.
The actual rule is that every weapon with a hex value less than that of Photon Claw will be reduced if it comes with a special that can be reduced (i.e. not sacrificial or elemental damage) and it strikes a target more than once per combo step, or is capable of striking more than one target per attack (excluding Cards). Specials of all other weapons are unreduced.
Melee weapons
Swords
Swords have a special reduction rate of 1/2.
Daggers
Daggers have a special reduction rate of 1/2.
Partisans
Partisans have a special reduction rate of 1/2.
Slicers
Slicers have a special reduction rate of 2/3.
Ranged weapons
Mechguns
Mechguns have a special reduction rate of 2/3.
Shots
Shots have a special reduction rate of 2/3.