The Onyx Blade is a greatsword with a dark, imposing presence, featuring a sleek, blackened metal blade that tapers to a sharp point. The blade is adorned with intricate, glowing purple runes that pulse with dark energy, suggesting its connection to the abyss. The hilt is wrapped in worn leather, providing a secure grip, and the crossguard is ornately designed with sharp, angular motifs that mirror the sword's menacing aura.