So, the Pool of Radiance FRG is not what I expected it to be, for its description. But I think we can have something fill its intended choke-point role, while being a bit more useful in combat.
The Elites are known to have grown great respect for humans and their fighting methods. As they are no longer bound by the Prophets’ will to limit their weapon technology, and after seeing (and feeling) how effective some human weapons were against both the Flood and the Covenant during the war, the following were created;
The TypeX-65 Blood Sealer
What I would do is have a non-scoped/linked firing mode be 3 plasma blob lobbing weapon that will kill an opponent in roughly the same time as a BiRi would. Fire pattern is similar to Titanfall’s Titan-used Triple Threat default fire but less spread (or more 
If only two blobs hit, the burning eventually kills an opponent, about 2-3 secs. If one hits, it would burn shields away and do about 50% health.
Players hit by the blobs are on fire and damage the teammates they touch. More about preventing/delaying a group of opponents from recharging than it is taking them down… BUT low health teammates might just succumb to the flames. Missed shots create a small AoE that is no different than a Spartan on fire.
Using Thruster can remove the burn!!!
That’s just the non-scoped firing mode. SCOPED zooms in just a little and the shots turn into an actual flame (thrower!!!). Somewhere sweet between the Shotgun and Scattershot best zones?
Shots are like a BiRi in that you consume a set amount and fire a stream of plasma for a set time. Vehicles and Spartans inside the flame are stunned/slowed.
Does not have afterburn like the blobs do, though the flames do “trace”. Damage is done inside the flame only.
Flame can be “Ogre-twitched” to create a wall of plasma… Or like a firework-sparkler tracer J
Technically a fullauto as it can just spray a constant flame in scope mode. If unscoped or one stops firing, the “fuel pocket” is still spent. Must swap weapons out to completely cancel a shot (but still use it up). Ie, Can’t hold a flame and just pop instantly into a regular shot BUT if you popped a shot, you can near immediately go into flame!
PS: BLUE FLAMING SPARTANS!!!
PSS: Reloading is definitely the one part I cannot imagine as there are a few ways, ie, just a single full charge like many Covenant/Elite weapons? A revolver-style ammo reserve? Single canisters/fuel stocks like a shotgun? It’s something to play with, not set.
Upgrade: TypeX-65i Brute Scorcher
Increased mag size. Increased vehicular damage and AoE damage. Things on fire are a nice red plasma.
Scoped mode fires 2 streams of plasma in a wider and less reaching stream. Ie, double damage to vehicles, or if sweeping, MUCH wider cone-of-effect. If only 1 regular shot is left, the twin flames last half as normal.
Fully upgraded: TypeX-65a Pyre of the Honored Kin
Increased RoF and mag size relative to default. Purple plasma.
Unscoped fires 3 plasma balls in a delta pattern that ricochet twice, unless impacting a Spartan, vehicle or explosion. Leaves an AoE damage pool for 1 second, 1 per ball after exploding (which would be similar to default as is).
Scoped fires a large single blob of plasma with a 1m proxy detonation and decently large napalm-like splash. Travels 10m or so, before exploding or is shot/tagged by an explosion. Leaves a rather large AoE damage pool that lasts for 3secs. Has slight target magnetism in that it will start to move towards an enemy target if it nears one. Players hit by the explosion and plasma die instantly. A full splash of plasma will take full shields down to 1/3 health.