From Halopedia, the Halo wiki
Armor effects are a special customizable option in the Armory in Halo: Reach, and for Halo: Reach and Halo 4 for The Master Chief Collection. Armor effects are visible in all gametypes, though they are not displayed in cutscenes.
On November 16, 2020, when Season 4: Reclaimer was released in Halo: The Master Chief Collection, it made them available to use on the Elites. In June 23, 2021, with the release of Season 7: Elite, these effects were added into Halo 4 as a new customization option.
The following effect occurs when the player is killed.
The following effect is continuously visible as long as the player is alive.
Legendary (Flaming Helmet)
The following effects are continuously visible as long as the player is alive, with a secondary effect when the player is killed.