To unlock the “Why Fight It?” Trophy in God of War, you have to upgrade the Blades of Chaos with a Chaos Flame. This Chaos Flame can only be bought at the shop after you finished the main story.
Travel to Muspelheim, The Realm of Fire and beat all trials until you fight against the Valkyrie at the top. She will drop “The Raging Inferno of Muspelheim” which can be traded for the Chaos Flame.
Return to the shop and upgrade the Blades of Chaos with the Chaos Flame to unlock the “Why Fight It?” Trophy and upgrade your Blades of Chaos.
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