After the slaying of Mahishasura and other demons by Goddess Chamundeshwari, there was no more use for her weapons
The Ayudha Pooja is a worship of whatever implements one may use in one's livelihood.
In its modern form Ayudha Pooja has become Vahana Pooja when people worship their vehicles including cars, scooters, and motor bikes.
All the machines/tools/vehicles are cleaned and decorated with sandal paste, turmeric and vermilion