Valor has many parts. Valor is honor. It is an unclear concept like love.
So you can pick a "part" of it and not need to exhaust every possibility. Like the part where the valorous one has the discretion execute his authority, the freedom to choose. If you want you could say that being discrete - cautious in words and deed is the better part of valor or you could say that youth, health, intellect or bravery are.
By choosing the part you like best you define its meaning to you. Is discretion even a small part of valor? Is forgiveness part of love or violence part of hate? Worse part /best part? It is not code.
I have never heard that quote. There is a quote that says, "Discretion is the better part of valor". This means that it's good to be brave and so on, but being careful and thinking things over before you act is more important.
In addition to other works where it might have appeared, it is in Shakespeare's "King Henry IV, Pt I," where the wording is, "The better part of valor is discretion."
Eight Is Enough - 1977 The Better Part of Valor 3-23 was released on: USA: 7 March 1979
Look before you leap. Think before you stick your nose into someone elses business.
Falstaff in Shakespeare's "Henry IV, Part One," says it.
You are probably thinking of this quotation from Shakespeare's Henry IV Part 1, spoken by Falstaff: "The better part of valour is discretion; in the which better part I have saved my life."
See the attached link for a brief explanation.
Valor
Valour (also spelled valor) is a noun.
Men without valor
A smiling face, the better part of valor.
"Courage".