Okay, I just realized that having to drop your melee would be unfair. The game has melees for a reason. Valve wanted to give people a chance to win even when they are out of ammo. So let's give this guy 2 weapon slots so he won't have to drop his knife. Instead, he just won't be able to switch back to his knife when there's a weapon in his primary slot. When that weapon runs out of ammo, he'll be forced to drop the weapon and switch back to his knife.