An interesting question.
First of all, circumstances dictate both the optimum choice in weapons, both from an ideal perspective and from a practical perspective.
The "ideal" weapon, of any type, is usually hypothetical, however. Practically speaking, whatever you have at hand is the reality you have to deal with.
You don't give us the details necessary to fully evaluate your circumstance. And, before you may post in response to this, I'm not asking for those details. I'm just posting this to clarify.
For example, "my potential assailant was within inches of my face and aggressively threatening to take my life" would not indicate to me that pepper spray would be your best option. It's difficult to maintain control of a situation if you unload a stream of pepper spray into your assailant's face when it's only a couple inches away from your own. Arms length or better, under ventilation conditions which minimize your own changes of getting a face full are optimal for this.
If what you are truely looking for is "non-lethal self defense", I would seriously recommend training in some form of martial arts. Martial arts focuses on many aspects that armed self-defense does...starting with situational awareness. It also teaches you both unarmed and armed forms, depending on your level of training and the types of martial arts you choose to pursue.
The advantage of martial arts training is that it's ALWAYS with you, no matter where you go and no matter what you have on hand. Such training allows you a great variety of options with respect to weapons of opportunity, too.
You do not have to be a total bad*ss in martial arts to make it count. Simply deflecting an attack, increasing the distance between you and an assailant, or executing a simple block, hold, throw, or other form of physical defense can give you an opening you need to either leave or incapacitate your attacker...with or without the use of deadly force as required.
Human interactions in conflict are a balance of four instinctive behavioral patterns: fight, flight, posture, and submission. How you interpret these behavioral patterns (for both yourself and your attacker) determines the weight you give to each. The ultimate resulting in the application of deadly force.
I applaud you for a variety of reasons...
1. You do not wish to use deadly force unless it's absolutely unavoidable.
2. You wish to increase your non-lethal options.
3. You have the brains to look back on your encounter with an analytical mindset and an eye to improve your options for possible future encounters.
Whatever you choose to do, choose wisely. And, God willing, I pray you never find yourself in such a situation again.