Press the button once, at home, in a quiet room. You'll flinch. It's a loud electric crackle with a bright blue arc jumping between the contacts — a sound the body reacts to before the brain catches up.
Compare what a spray asks. It's a cloud, and the air gets a vote — wind can push it back into your face, and indoors it thickens around both of you. It only counts if it lands in the eyes, on a moving face, past glasses or a hood.
Nothing leaves the Velunex. No cloud to blow back, nothing that drifts onto a friend or a dog, no small target to hit while your hands shake.
And you were never going to fight anyone. You needed him to stop for two seconds so you could reach the door, get in, and lock it. The sound does that from six feet away. Most of the time, that's where it ends.
And if it doesn't, the button is right there under your thumb.