The Wristblades are a standard weapon and every Predator in every movie has them in some form. Generally, a Predator has two serrated blades located on both wrists which can be extended from the wrist gauntlet. It’s unknown what the blades are made out of but I suspect it’s some form of strong metal. The wristblades are pretty much the last form of defence for the Predator and are especially useful in melee combat. As a last resort, they can be fired from the wrist gauntlet as a projectile.
In the first Predator, Dillon, one of the commandos, is definitely killed by the Predator’s wristblades while Hawkins and Billy may have been killed by them too. What’s unique though to this Predator is that he is able to extend the blades outwards as he was able to pin Dutch’s head in between the blades. This wouldn’t have been possible because of the narrow width between the two blades.
Predator 2 (1990)
In Predator 2, City Hunter uses the blades throughout the movie and they’re extremely similar in design to the Jungle Hunter’s. The gauntlets were made separately with hard or rubber pieces whereas in the first film, they were made of foam rubber onto the suit itself. The allowed the blades to come in and out easily because the mechanisms were built from a much harder piece.
Alien vs Predator (2004)
In Alien vs Predator, both Scar and Celtic can extend their wristblades to double the length. They’re much longer than seen in the previous two Predator movies and only the Upgrade Predator in The Predator has longer blades. The Predators can also revert their wrist blades to point the other way as proven by the Celtic Predator when he sliced off part of the Grid Alien’s tail. Lastly, the blades can also be fired as a weapon as shown by the Scar Predator when he fired the blades at the Queen Alien. This is most likely a last resort kind of use.
One thing to note is that the wristblades are not acid-resistant which was a surprise to the Celtic Predator when acid from the Grid Alien disintegrated his wristblades. I think you can argue that this was deliberate as the reason the Predators were down there was because it was a rite of passage. It would have been too easy for them if every weapon was acid resistant.
Aliens vs Predator Requiem (2007)
In AvP Requiem, Wolf has similar wristblades to Jungle Hunter and City Hunter. Two pairs of blades on both wrist gauntlets can be extended at will. We see him kill somebody using them in the forest and he uses them against the Predalien and a Xenomorph in the hospital later on. Interestingly, unlike the Celtic Predator’s, Wolf’s wristblades are acid resistant.
An early design for the wristblades from Farzad Varahramyan had metal claws similar to the Wolverine or Freddy Krueger.
The wristblades feature in Predators although they’ve been given a overhaul. The Super Predators have only one blade on their right arm. The Tracker Predator kills Nikolai by impaling him with a blade and the Falconer Predator kills Hanzo with the blade. The Berserker Predator also decapitates the Classic Predator with the blade. The blade can also be fired as a weapon as seen in Alien vs Predator. Near the end of the movie, the Berserker fires it at Isabelle after she shoots him with the sniper rifle.
The Classic Predator has the twin wristblades like Jungle Hunter and City Hunter. He use them in the battle with the Berserker Predator.
The Predator (2018)
When the Fugitive Predator escapes and recovers his weaponry and equipment, we can see he has a singular blade on his right wrist. This time however, instead of the blade being fixed on his wrist like previous Predators, the blade emerges from inside of his wrist gauntlet. Like previous Predators, the blade can be fired at targets. When Quinn McKenna fires at Fugitive, the Predator turns around and fires the blade at him. A few seconds later, Fugitive takes out the Marines in the truck, Fugitive has a new blade in its place.
I guess when Scar and Berserker Predators fired their blades, it was a last resort weapon and it couldn’t be replaced once fired whereas Fugitive can replenish his blades as they are within the gauntlet itself. The blade isn’t indestructible though. When Fugitive used his blade against Upgrade’s tough skin armour, it broke as soon as it made contact.
The Upgrade Predator also has a singular blade on his right forearm and this is the longest blade out of all Predators seen so far, probably due to Upgrade’s enormous size. It functions in the same way as Fugitive’s. Firstly, Upgrade’s blade can be fully retracted inside of the wrist gauntlet but it can also be fired as we saw him fire it at Casey in the forest.