In the near-future story I'm working on the protagonist is prepared for a wide range of possibilities, including getting outnumbered and surrendered.
For that possibility i though about a Banshee Box that the protagonist wears in the back at nape-level that emits an ear-hurting sound for the baddies to stop pointing their weapons to cover their ears (the protagonist uses electronic ear protection to counter that), and then launches guided spikes steered by retractable fins and cannards to the targets marked with the AR contacts.
The spikes penetrate their necks and injects a flammable gas to expand the wound cavity, that is then ignited for a decapitating explosion.
They have a very limited range and can't do very sharp turns, besides being expensive to make so it's basically a last resort for giving the character a chance to escape.
My inspirations were Mando's Whistling Birds, Yondu's Arrow and injection knives.
But there's still one inspiration that i'm still deciding if i should include, that is tri-edged daggers like the Jagdkommando and the M84 Cyclone.
Now i know, i know, these are obviously mall-ninja weapons that if something, makes stabbing more difficult because you would need to stab and twist at the same time for it to be effective, it can still be effective if the blade rests on a bearing that enables it to spin freely and screw through the flesh. The point is that for spinning projectiles, having a twisted blade can help it penetrate and then twist inside bones, breaking them and making penetration easier.
I even thinkered with the idea of a ballistic tri-edged injection knife, that was later incorpored into the Banshee Box.
But I,m not sure about the tri-edged part, because the ideal would be for the gas to not escape through the entry wound and i'm not sure if a spike would seal it better, though i'm also thinkering with some sort of vedative piece at the base that could work for both designs, and then I'd go for the one that penetrates better and has the best aerodynamics, maybe a mix of the two, the gas has to be stored inside of it anyway.
I'm open to other options.
Edit: It has been shown to me how unncessarily overkill it would be for the spikes to be hypersonic at such a a close range, so i edited it out and now the answers can focus in the aerodynamics, penetration and sealing of the shapes.