Back to the original topic... the term "Self Defense" is slightly nebulous, but many would agree it involves protecting life (your's or family) from threats, and that SD technially ends once the threat no longer is imminent. Armed vs unarmed both can fall into the category of SD depending on your preference, what is available to you at the time, and what level of force was appropriate.
After the fact, if legal action occurs, you may then have to justify your SD actions to a jury who are safely sitting in a jury box with an armed bailiff to protect them. This is sometimes your most perilous time. The jury gets to decide the apropriateness of your actions from a safe, sterile setting with no danger, fear, or adrenaline. The may decide the lifetime career criminal whose arm you crippled with a well executed jujigatame was destined for a future as a neurosurgeon, and you just ruined his life... justifying him recieving huge compensation from you.
So even if you do everything "right", there's always a chance someone else will disagree.
I absolutely agree with the above. Self-defense is both a personal decision as well as a legal term in that sense, and it may not mean the same thing in both arenas.
I believe it is wise to be familiar with the laws of self-defense where you work and live, and to keep in mind that just because a person believes that they engaged in legitimate self-defense, that doesn't mean they cannot be arrested, charged with a crime, sued, etc. That doesn't mean one should take a beating, acquiesce to a robbery, or otherwise become an intentional victim; it just means one must be aware that actions have consequences, even when things are done as they should be.
I do not propose that one should live their life on their knees, on the contrary. However, I do believe that it is wise to avoid situations that might require a person to defend themselves with violence, like getting into road-rage arguments, fights in bars, etc. If you don't let yourself get into those situations, you won't have to deal with the consequences even when you might be in the right both legally and morally.