A close up of a bird sitting on a branch in a forest

Create a detailed description of 'Nocturno,' Benny's loyal raven companion in the desolate, post-human fantasy world. Nocturno should be a visually striking character, simple in form and entirely within the natural realm of a raven. He should have sleek, iridescent black feathers that shimmer with hints of deep blue and purple when caught in the light. Nocturno's eyes should be piercing and enigmatic, with bright, almost unnaturally blue irises that seem to hold ancient wisdom. His beak should be sharp and sleek, with a faint glint of silver at its tip. Nocturno's wingspan should be impressive, showcasing his agility and grace as he soars through the darkened skies. He should have one distinctive feature—a single, delicate feather on his left wing, which stands out as it possesses a subtle luminescence, casting a soft, ethereal glow in the moonlight. Nocturno's demeanor should exude a sense of both intelligence and mystery. He should have an uncanny ability to communicate with Benny through a combination of subtle body language and hauntingly melodious caws. His presence should be both comforting and enigmatic, embodying the essence of an otherworldly creature in this post-human landscape. Describe any additional unique characteristics or behaviors that make Nocturno stand out as an extraordinary companion to Benny, while ensuring that he retains the characteristics of a raven.