Weapon Devils

The Weapon Devils (武器の悪魔) was a group of 7 devils that previously served under the Four Horsemen, each member embodies the fear of a certain type of weapon. Every Weapon Devil are now currently fused with a human.

History
There isn’t much information about the Weapon Devils before they are fused with their respective human, with very little information provided by Makima. The Weapon Devils once fought alongside the Four Horsemen against Pochita, but at the height of the battle, Pochita vanished and is reduced to a completely changed, near-death state and ended up on Earth.

The Weapon Devils also somehow ended up on Earth, whether it’s because they were killed in the battle and reincarnated or not is unknown. They later become fused with different humans all throughout the world, thus creating 7 new hybrids.

Trivia

 * Depending how long each Weapon Devil has been fused to their respective hybrid, there could be a bit of a contradiction in how they were able to fight the Chainsaw Man as a group of Devils in Hell. Given how one of them was even fused with someone who was claimed to be "the first devil hunter" who is of very ambiguous age this adds further to the question.
 * It is possible they could have been in a state, similar to Pochita near the end of Part 1, where they took control over the hybrid body and went to hell in some way to fight the Chainsaw Man but this remains unknown.