[Brian Pfleuger]

Any weapon creates a disparity of force.

There are basically three elements of a lethal force scenario. Opportunity, Ability and Jeopardy.

Your would-be attacker must have all three if you are going to be justified in using deadly force against them.

Pepper spray or a taser goes to ability. They certainly give the attacker the ability to harm you and you have no idea nor cause to believe that the harm would end at the simple use of one of them and it's entirely possible that the taser in particular could be deadly in several ways, such as hitting your head when you fall or perhaps you have a heart condition.

Opportunity is essentially the question of whether or not the attacker is close enough to do what he wants to do. Being on the other side of a river might give him opportunity if he has a gun, not so much with pepper spray or a taser.

Jeopardy essentially means are you really in danger. Would a "Reasonable and prudent" person believe that they were about to be attacked by a person who meant to do them severe harm.

Finally, some jurisdictions, and indeed common sense, dictate that if there is some reasonable manner of escape for you and all other innocent parties, you must make use of that avenue.

So, complex question, there's more than "what if he has X".