The “best exospine stellar blade” is a hypothetical weapon that has yet to be created. However, based on the individual words, we can infer that it is likely a type of sword or blade that is made of a strong and durable material, possibly exospine, and is designed for use in stellar combat or space exploration.
Such a weapon would be highly valuable for soldiers, explorers, and adventurers who need to defend themselves or perform tasks in the harsh and unforgiving environment of space. It would also be a powerful symbol of strength and technological prowess.