On the Disintegration page, I made an addition to the page by adding certain Promethean weapons from Halo 4 and 5, and that same day, my edits were removed by an admin, whom I'm not going to name. I believe my contribution was valid and shouldn't have been removed.
The Promethean weapons—the LightRifle, Scattershot, Binary Rifle, Incineration Cannon and Pulse Grenade—upon death, disintegrate the victim of the user of the weapons to prevent the Flood species from repurposing any form of biomass.
They emit ionized particles as their ammunition, technically plasma.
The victim's body's divides into smaller particles and they eventually turn to dust.
This isn't much of a reason, but the official Halo wiki, Halopedia, describes the weapons.