A mystical blade created from the amalgam of two separate enchanted skein's wielded by former royalty, each hailing from both the Kree and Skrull Emperium's of old. When the progeny of the warring king and queen was born he had their two swords merged into one mighty blade of unknown science-magical prowess.
This Successor to the throne was called Dorrek Supreme, heir to the royal thrones of both space faring empires who brought others sharing his hybrid lineage together for protection against the xenophobic cruelty of their parent species; thus creating the Knights of Infinity.
With this magical sword in tow both he and those of his bloodline wielded the power and the right to lord of the Kree, Skrull and their mixed breed off-shot's as king of all space. The blade could only be wielded by those of the Supreme bloodline as an enchantment had been cast on it in order to protect and select successors to the royal line.
The sword Excelsior has a host of uncatalogued powers, possibly on a quantum mystical scale as it enabled its wielders to lord over the cosmos. While most of its abilities are a mystery the blades foremost attribute is a worthiness enchantment which only enables those of its first wielders descendancy to use it. Another attribute is the absorption and negation of potent magic cast by even the most astute of sorcerer's like Moridun, its edge can also cancel out the existence of other-dimensional entities as well.