All Out Defence is a combat action option in some games, useful for either when you want to concentrate on not getting hit because you're on the back foot, or for when you don't necessarily want to hurt your opponent. So it can be good for allowing yourself to try to talk your opponent out of attacking - assuming you think that's a sensible option.

Don't underestimate All Out Defence, as a good roleplayer can talk pretty much anyone out of anything.

Transcript

Luke: Why does it always end up with the sword fighting?
[SFX]: kzzrzzkk!
Darth Vader: You were the one who drew your sword.
[SFX]: Whooom!
Luke: I didn't want to fight! I just wanted to kill the Emperor.
Darth Vader: Oh. My misunderstanding.
[SFX]: Whooom!
[SFX]: Whooom!
[SFX]: Whooom!
Luke: He practically asked me to kill him. He's tormented by his conscience. And, by the way, removing him is the key to bringing peace to the Galaxy.
Luke: Let! Me! Past!
[SFX]: Kiiick...!!! {kicks Vader down stairs}
Palpatine: This is madness! I've done naught but strive for peace; yet the Galaxy burns around me! And in my very chambers! What more can I do?!
Luke: Have you tried taking up the fiddle?
[SFX]: whmmmm...