Ninja~ the user basically has traits of a 'ninja' there are alot of abilities that can come with it (these are some but you can add anything else).
Sword~ the user can make swords appear in their hands whenever they want, they have amazing sword skills and when using it can move at the speed of lightening (I based this part off zenitsu amd other characters from demon slayer, think of it as how they use their swords against demons).
Absolute silence~ when they hold their breath or breathe in a certain way (again heavily inspired by demon slayer) they can in a sense 'dissappear' they don't actually disappear as in go invisible but its impossible to see them.
Breathing technique~ this doesn't really need much explaining, you don't have to include this part but its based of demon slayer breathing techniques.
Ninja star~ user can also use ninja stars also known as shuriken, with this they have enhanced aim and catching (if that makes sense)
Ninja barrier~ using their sword or whichever weapon they want, they can create invisible barriers that can't be penetrated.
The user will also have enhanced fighting and martial art skills/other fighting techniques and types and enhanced senses. Honestly I think this would be a great villain quirk, it's not like you can really use your weapons if your a hero.
Possible hero/villain names~
~ninja (idk this was kinda obvious)
~slayer
~silencer
~silent killer
~blade
~killing star