The Whip is a brand new weapon that was featured in 2007’s AvP Requiem. When Wolf receives the distress call one of the weapons he picks up the 10ft Whip. Wolf uses it at the end of the film on the hospital rooftop against a Xenomorph and it cuts it in half. Although not stated in the movie, the directors have said that it is in fact made out of Alien tails which is the reason the blades easily split the creatures in half and are unaffected by the acid.
An early design for the whip from Farzad Varahramyan actually had the whip being inside a handle which would extend depending on how far the Predator wanted to reach. This design had an Alien’s tail on the tip. This idea was similar to the Upgrade Predator’s ‘Harpoon‘ weapon in The Predator although his was integrated into his wrist gauntlet.