The Weapon Governor was designed to deny the Infected access to personal arms. All Lasrian (and Agency soldiers) carry weapons fitted with a Governor. It is essentially a small explosive attached to the firing mechanism. When an Infected picks up the weapon, the Governor will activate, flash red for around 10 seconds before eventually detonating. Up until then the gun can be used without problem. The explosion itself does not harm Hayden if he is holding the weapon but there will be a blinding flash before it is rendered useless.
Part of the Black Market Salesman's ploy to charge for weaponry is that welding Governors off guns (and therefore allowing Hayden to use them) is a tricky task.
- Considering that the Governor featured on the sniper's VX Carbine has such a long lifespan, while explosive weapons completely lack one, it is likely that the Governor acts as a proximity detonator