This kind of equipment was called artifacts in Etrium and resulted from the crafters' work. Lately, Etrium crafters learned how to use thaids' body parts, but it was still a relatively new technology, and the crafters mostly used ores.
However, aside from their brain crystal powers, melee soldiers and mercenaries usually preferred to use weapons as their main attacking tools since they only had to pay for their maintenance and didn't need bullets.
On the contrary, ranged units preferred guns or weapons related to their brain crystal powers. Camille and Ramon, and almost all the members of the band of giants, were preparing themselves for an urban fight.
They were previously briefed on the fact that millions of creatures entered the city and started slaughtering the citizens still inside the city and those who could not reach a shelter on time. Still, they didn't receive any orders yet, only to prepare themselves.