Ripper

Ripper left the game together with the 2020 Halloween Event, where it sat on the 29th tier of the Main Event. Whoever bought that tier received the knife; everybody else now has to trade for it, because the event is over. The wiki classes it as a Legendary knife.

The blade

The blade is built from dark bricks, with silver spikes attached to it that run over a lime green edge. The guard is silver and the handle is solid black with silver points. The result is a dark, studded weapon with a single bright green line along the cutting side.

Partner gun

A gun with the same name, Ripper (Gun), is listed as its partner. The knife page only points to the gun by name, and the knife itself came from the Main Event track rather than from a box. The curated data lists tiers 2 to 30 of that Main Event at 600 Candies each, which would put tier 29 inside that range, but the wiki page states only the tier number and not a price. Today trading is the only route to owning it, and the terms depend on the player on the other side of the deal.