Thetis

A bipedal machine weapon. These machines can share any information they gather between them, which makes them quite formidable once any one of them identifies its enemy's weakness. These weapons battle based on accumulated data, but because humans can change quite drastically, they seem to encounter issues when facing humans. Supporting this are reports of adventurers easily dispatching these weapons in their next encounter against them after the adventurers gained power in a short frame of time.