I have 1 suggestion I don't know if this is used or not but
T weapon: Tomahawk, not a missile but an axe (you could call it an axe so it doesn't get confusing)
So this is a 1 shot insta kill melee weapon, though unlike the knife you have to throw it and it makes a low-loud noise on hit, if it misses you cannot pick it up again and detectives can dna scan it. Yeah I know pretty stupid right???

My opinion, it sounds good yes, But you can throw a knife cant you? If you cant it is a great idea, but if you can it would be the exact same, but different look and sound.
Good thinking.

An attachment for t's, you can buy, Damage Upgrade (Upgrade the damage you do to other players, with weapons and crowbar.)

I was asking so I guess that I should throw some ideas around;

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T WEAPONS:
A Radio Jammer, Cuts off Voice nd type chat. It makes a loud sound so people can find it and destroy it.
Turtle Bomb, Throw it and several turtles spread out and if you go near it they start attacking you. (Seen this on a server)
An identity stealer, It looks like a knife but what it does is steal someone's name. Doesn't kill them. (Seen this on a server)
Prop Disguiser, You shoot the pistol and you then turn into a prop for a set amount of time. (Seen this on a server)
Reverse Discombob - Sucks entities inward toward centre of explosion.
Cannibalism - Allows you to eat a corpse to destroy evidence and restore health. (Seen this on a server)
Death Faker, Fake your own death, but if you get spotted BAD LUCK.
Turrent, Place it down and it fires at anyone who walks past.

D WEAPONS:
DNA SCANNER Upgrade, It makes the DNA scanner into a better one so it finds the DNA more rapidly.
Freeze Grenade, It freezes people in place.
Camera, Place a camera and a small screen appears in the corner of your screen. Sit back and watch.
Junior Detective, You assign someone to be your junior detective, He gets a DNA Scanner and can see where you get called to. But no Detective shop.

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Also a "!gettraitor" command so you know who the last T's are instead of asking. http://steamcommunity.com/sharedfiles/filedetails/?id=289107172&searchtext=%21gettraitor

Sorry I know there is a lot but just ideas.