Generate a full-body image of a valiant medieval knight. He is clad in highly detailed, ornate plate armor, featuring a distinctive, golden banana-shaped crest prominently adorning the top of his helmet, seamlessly integrated into the armor's design with a regal yet whimsical aesthetic. The knight stands in a heroic, resolute pose directly in front of the majestic, crumbling stone ruins of an ancient castle, which are partially overgrown with ivy and moss. The scene should be rendered with dramatic, atmospheric lighting, highlighting the intricate textures of both the armor and the weathered castle ruins, under a brooding, epic sky. The overall style should be photorealistic with a touch of fantasy.