I have a few problems with this.

1: Scouts have the most stamina, and would be killed in roughly 3 seconds by this (Most non-proto scout suits have <250 total HP). Coupled with the fact that most scout weapons (shotgun) are short range, this already seems like a bad idea.

2: It appears to be an area of affect weapon, which in most games are quite powerful (because you can often damage a lot of enemies at once, often times, without accurate shot placement, or even seeing them. Also, AOE weapons are hard to avoid), while merely giving up a low slot. To balance, this would need to take at a minimum an equipment or grenade slot, and more reasonably a secondary or primary weapon slot.

3: How do you counter this module? You can't shoot a non-moving module, as it is part of your suit (perhaps they have to kill you, which then becomes a larger task, since this is only a low slot module, and not a weapon, because you can fire back) You can simply fit it onto a faster suit, and then chase people as they run away. And as you lose stamina, you lose the ability to run away. It would simply be too overpowered for a very minimal trade off. Imagine a fully tanked (4 plates, multiple shield extenders) squad of guys running shoulder to shoulder taking .5 seconds to kill a heavy without firing a shot or even seeing them. Want to sneak up on them with a shotty and take them out? Not gonna happen with this bad boy, you snuck up on your opponents, was about to shoot them, and died- they never knew you were even there.

While I applaud you ability at thinking outside the box, your idea needs quite some polishing to become fair.

How would this affect cloaked scouts? This seems like it would be rather bad for that particular community if it could be equipped in a simple low slot. Hell I forgo armor all the time with my scout honestly, just have dampeners and a code breaker on it. Both enhanced and Im still plenty lethal.