The injector gives:
These are certainly not useless. If anything these are pretty strong advantages to have. There's only two problems. The first is the duration, which is so short that you don't have enough time to make something happen. The second is that the injection animation takes too long and makes you vulnerable.
In my opinion, it's not that the injector doesn't do enough, instead it's the opposite, it does too much. If the injector only buffed movement speed, or only improved sound detection, they could balance it in a way where it would have a much longer duration. If they significantly improve the duration with its current effects it could very easily go from the useless gadget it is now, to being insanely strong.
So here's what I'd suggest. I'd split the adrenaline injector into multiple different injectors. You pick which effect you want to run with. Each injector has a different duration, depending on how strong the effect is. On average, the duration would probably be around 3x to 4x as long as it is now.
